Summary of knowledge points frequently used or not commonly used in iOS development, several years of collection and accumulation (stepped on the pit).

A, the iPhone Size

Mobile phone models The screen size
iPhone 4/4s 320 * 480
iPhone 5/5s 320 * 568
iPhone 6/6s 7 8 375 * 667
iPhone 6plus/6s plus/7 plus/8 plus 414 * 736
iPhone X/Xs 375 * 812
iPhone XR 276 * 598
iPhone Xs Max 414 * 896

2. Set the title color for the Navigation Bar

UIColor *whiteColor = [UIColor whiteColor];
NSDictionary *dic = [NSDictionary dictionaryWithObject:whiteColor forKey:NSForegroundColorAttributeName];
[self.navigationController.navigationBar setTitleTextAttributes:dic];
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How to store a CGPoint in an array

CGPoint itemSprite1position = CGPointMake(100, 200); NSMutableArray * array = [[NSMutableArray alloc] initWithObjects:NSStringFromCGPoint(itemSprite1position),nil]; CGPoint point = CGPointFromString([array objectAtIndex:0]); NSLog(@"point is %@.", NSStringFromCGPoint(point));
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You can use NSValue to store basic data, which is much clearer.

CGPoint itemSprite1position = CGPointMake(100, 200); NSValue *originValue = [NSValue valueWithCGPoint:itemSprite1position]; NSMutableArray * array = [[NSMutableArray alloc] initWithObjects:originValue, nil]; NSValue *currentValue = [array objectAtIndex:0]; CGPoint point = [currentValue CGPointValue]; NSLog(@"point is %@.", NSStringFromCGPoint(point));
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NSMutableArray

*array now supports generics in Xcode7.

4. UIColor gets RGB values

UIColor *color = [UIColor colorWithRed:0.0 green:0.0 blue:1.0 alpha:1.0];
const CGFloat *components = CGColorGetComponents(color.CGColor);
NSLog(@"Red: %f", components[0]);
NSLog(@"Green: %f", components[1]);
NSLog(@"Blue: %f", components[2]);
NSLog(@"Alpha: %f", components[3]);
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5. Modify textField placeholder font color and size

self.textField.placeholder = @"username is in here!";
[self.textField setValue:[UIColor redColor] forKeyPath:@"_placeholderLabel.textColor"];
[self.textField setValue:[UIFont boldSystemFontOfSize:16] forKeyPath:@"_placeholderLabel.font"];
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Setting this using attributedString is recommended.

NSString *string = @Brave New World;
    NSMutableAttributedString *attributedString = [[NSMutableAttributedString alloc] initWithString:string];
    
    [attributedString addAttribute:NSForegroundColorAttributeName
                             value:[UIColor redColor]
                             range:NSMakeRange(0, [string length])];
    
    [attributedString addAttribute:NSFontAttributeName
                             value:[UIFont systemFontOfSize:16]
                             range:NSMakeRange(0, [string length])];
    
    self.textField.attributedPlaceholder = attributedString;
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The distance between two points

static __inline__ CGFloat CGPointDistanceBetweenTwoPoints(CGPoint point1, CGPoint point2) { CGFloat dx = point2.x - point1.x; CGFloat dy = point2.y - point1.y; returnsqrt(dx*dx + dy*dy); }Copy the code

7, IOS development – close/close keyboard method summary

1. Press the Return button to fold up the keyboard

- (BOOL)textFieldShouldReturn:(UITextField *)textField 
{
    return [textField resignFirstResponder]; 
}
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2. Click the background View to close the keyboard

[self.view endEditing:YES];
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3, You can add this sentence anywhere, can be used to unify the keyboard

[[[UIApplication sharedApplication] keyWindow] endEditing:YES];
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Note when using imagesqa. xcassets

When you drag an image directly into imagesqa.xcassets, the name of the image remains. If the name of the image is too long, the name will be stored in imagesqa.xcassets. If the name is too long, the SourceTree will fail.

UIPickerView judge from start to end of selection

To start with, you need to inherit UiPickerView, create a subclass, and override it in that subclass

- (UIView*)hitTest:(CGPoint)point withEvent:(UIEvent*)event
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When [super hitTest:point withEvent:event] returns not nil, the UIPickerView is clicked. End the selected delegate method that implements UIPickerView

- (void)pickerView:(UIPickerView*)pickerView didSelectRow:(NSInteger)row inComponent:(NSInteger)component
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When this method is called, the selection is over.

IOS simulator keyboard events

When the iOS emulator selects Keybaord->Connect Hardware Keyboard, the keyboard does not pop up.


When added to the code

[[NSNotificationCenter defaultCenter] addObserver:self
                                             selector:@selector(keyboardWillHide)
                                                 name:UIKeyboardWillHideNotification
                                               object:nil];
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Get keyboard events. – (void)keyboardWillHide. Will not be called in this case. Because there is no keyboard hide and show.

Black on top and bottom after using size classes

After using size classes, the top and bottom sections of the ios7 emulator appear black

This can be done by going to General->App Icons and Launch Images->Launch Images Source and setting images.xcassets.

Set different sizes to size classes

Font sets different size classes.

Update UILabel text in thread

[self.label1 performSelectorOnMainThread:@selector(setText:)                                      withObject:textDisplay
                                   waitUntilDone:YES];
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Label1 is UILabel, which can be used to update text when it is needed in child threads. All the other UIViews are the same.

14, use UIScrollViewKeyboardDismissMode implements the Message app

The ability to make the keyboard disappear while scrolling, like in the Messages app, is a great experience. However, integrating this behavior into your app can be difficult. Fortunately, Apple has added a nice property called keyboardDismissMode to UIScrollView to make it a lot easier.

Now just change a simple property in the Storyboard, or add a line of code, and your app can do the same thing as a Messages app.

This attribute is used a new UIScrollViewKeyboardDismissMode enum enumerated types. The possible values for this enum enum type are as follows:

typedef NS_ENUM(NSInteger, UIScrollViewKeyboardDismissMode) {
    UIScrollViewKeyboardDismissModeNone,
    UIScrollViewKeyboardDismissModeOnDrag,      // dismisses the keyboard when a drag begins
    UIScrollViewKeyboardDismissModeInteractive, // the keyboard follows the dragging touch off screen, and may be pulled upward again to cancel the dismiss
} NS_ENUM_AVAILABLE_IOS(7_0);
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Here are the properties you need to set to make the keyboard disappear when scrolling:

Referenced from: “_sqlite3_bind_blob”

Load sqlite3. Dylib into the framework

Statusbar text color

The status bar by default font color is black, to change for the needs of the white in the infoPlist UIViewControllerBasedStatusBarAppearance to NO, then add in the code: [application setStatusBarStyle:UIStatusBarStyleLightContent];

Get the current hard drive space

NSFileManager *fm = [NSFileManager defaultManager];
    NSDictionary *fattributes = [fm attributesOfFileSystemForPath:NSHomeDirectory() error:nil];

    NSLog(@"% lldG capacity",[[fattributes objectForKey:NSFileSystemSize] longLongValue]/1000000000);
    NSLog(@"Available" % lldG,[[fattributes objectForKey:NSFileSystemFreeSize] longLongValue]/1000000000);
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18. Set the transparency of UIView without affecting other sub views

UIView sets the alpha value, but the content becomes transparent as well. Is there a solution?

Set the opacity of the background color color

Such as:

[self.testView set[UIColor colorWithRed:0.0 green:1.0 blue:1.0 alpha:0.5]];Copy the code

If you set the alpha of color, you can achieve transparency of background color. When other sub views are not affected, add alpha to color, or change the alpha value.

// Returns a color inthe same color space as the receiver with the specified alpha component. - (UIColor *)colorWithAlphaComponent:(CGFloat)alpha; / / eg. [the backgroundColor colorWithAlphaComponent: 0.5];Copy the code

19. Convert color to UIImage

UIImage - (UIImage *)createImageWithColor:(UIColor *)color {CGRect rect = CGRectMake(0.0f, 0.0f, 1.0f, 1.0f);  UIGraphicsBeginImageContext(rect.size); CGContextRef context = UIGraphicsGetCurrentContext(); CGContextSetFillColorWithColor(context, [color CGColor]); CGContextFillRect(context, rect); UIImage *theImage = UIGraphicsGetImageFromCurrentImageContext(); UIGraphicsEndImageContext();return theImage;
}
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NSTimer

NSTimer *timer = [NSTimer scheduledTimerWithTimeInterval:.02 target:self selector:@selector(tick:) userInfo:nil repeats:YES];
    
    [[NSRunLoop currentRunLoop] addTimer:timer forMode:NSRunLoopCommonModes];
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Add a timer to NSRunLoop.

21, Bundle Identifier application identifier

Bundle Identifier is an application identifier that distinguishes an application from other apps.

NSDate retrieves the time several years ago

Eg. Get the date 40 years ago

NSCalendar *gregorian = [[NSCalendar alloc] initWithCalendarIdentifier:NSGregorianCalendar];
NSDateComponents *dateComponents = [[NSDateComponents alloc] init];
[dateComponents setYear:-40];
self.birthDate = [gregorian dateByAddingComponents:dateComponents toDate:[NSDate date] options:0];
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Hide the StatusBar when loading the iOS startup image

Simply add Status bar is INITIALLY Hidden to info.plist and set it to YES

24. IOS development, mixed use of ARC and non-ARC in projects

In Xcode projects we can use a mixture of ARC and non-ARC modes.

If your project uses non-ARC mode, add the -fobjc-arc tag to the ARC mode code files.

If your project uses ARC mode, add the -fno-objc-arc tag to non-ARC code files.

Methods for adding labels:

  • Open: your target -> Build Phases -> Compile Sources.
  • Double-click the corresponding *.m file
  • In the pop-up window, enter the aforementioned tabs -fobjc-arc / -fno-objC-Arc
  • Click Done to save

Twenty-five, boundingRectWithSize: options: attributes: context: the use of computed text size

Before using the nsstrings class sizeWithFont: constrainedToSize: lineBreakMode: method, but this method has been iOS7 Deprecated. And new out an boudingRectWithSize iOS7: options: attributes: the context method instead. How do you use it, especially that attribute

NSDictionary *attribute = @{NSFontAttributeName: [UIFont systemFontOfSize:13]};
CGSize size = [@"Relevant nsstrings" boundingRectWithSize:CGSizeMake(100, 0) options: NSStringDrawingTruncatesLastVisibleLine | NSStringDrawingUsesLineFragmentOrigin | NSStringDrawingUsesFontLeading attributes:attribute context:nil].size;
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Note the use of NSDate

NSDate The best time to save and transfer data is UTC.

Change the time to the local time when it is displayed to the user.

Present problem of a UIViewController property in UIViewController

If there is A property property UIViewController B in UIViewController A, after instantiation, add vbC. view to the main UIViewController A.view, If done on viewB – (void)presentViewController:(UIViewController *)viewControllerToPresent animated: (BOOL)flag completion:(void (^)(void))completion NS_AVAILABLE_IOS(5_0); The operation will appear, “**Presenting view controllers on detached view controllers is discouraged **” problem.

BVC has been present in AVC, so it will be wrong to try again.

You can use

[self.view.window.rootViewController presentViewController:imagePicker
                                                      animated:YES
                                                    completion:^{
                                                        NSLog(@"Finished");
                                                    }];
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To solve it.

UITableViewCell indentationLevel

The UITableViewCell attribute NSInteger indentationLevel is used to set the indentationLevel value for the cell.

There are CGFloat indentationWidth; Property to set the width of the indentation.

Total indentationWidth: indentationLevel * indentationWidth

ActivityViewController shares using AirDrop

Share using AirDrop:

NSArray *array = @[@"test1"The @"test2"];

UIActivityViewController *activityVC = [[UIActivityViewController alloc] initWithActivityItems:array applicationActivities:nil];

[self presentViewController:activityVC animated:YES
                 completion:^{
                     NSLog(@"Air");
                 }];
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You can pop up the interface:

Get height of CGRect

CGRect height, in addition to the self. CreateNewMessageTableView. Frame. The size, height, do some grammar acquisition.

You can also use CGRectGetHeight (self) createNewMessageTableView) frame) for direct access.

In addition to this method there is func CGRectGetWidth(rect: CGRect) -> CGFloat

And so on

func CGRectGetMinX(rect: CGRect) -> CGFloat
func CGRectGetMidX(rect: CGRect) -> CGFloat
func CGRectGetMaxX(rect: CGRect) -> CGFloat
func CGRectGetMinY(rect: CGRect) -> CGFloat
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31. Print %

NSString *printPercentStr = [NSString stringWithFormat:@"% %"];
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32. Check whether IDFA is used in the project

allentekiMac-mini:JiKaTongGit lihuaxie$ grep -r advertisingIdentifier . grep: ./ios/Framework/AMapSearchKit.framework/Resources: No such file or directory Binary file ./ios/Framework/MAMapKit.framework/MAMapKit matches Binary file . / ios/Framework/MAMapKit. Framework/Versions/against 2.4.1 e00ba6a/MAMapKit matches Binary file ./ios/Framework/MAMapKit.framework/Versions/Current/MAMapKit matches Binary file ./ios/JiKaTong.xcodeproj/project.xcworkspace/xcuserdata/lihuaxie.xcuserdatad/UserInterfaceState.xcuserstate matches allentekiMac-mini:JiKaTongGit lihuaxie$Copy the code

Open terminal, go to project directory, type:

grep -r advertisingIdentifier .
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You can see that IDFA is used in those files and if it is used it will be displayed.

33. APP blocks trigger events

// Disable user interaction when download finishes
[[UIApplication sharedApplication] beginIgnoringInteractionEvents];
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34. Set the Status bar color

Status bar color Settings:

  1. If there is no Navigation bar, set it directly
// make status bar background color
self.view.backgroundColor = COLOR_APP_MAIN;
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  1. If there is a Navigation bar, add a view to the navigation bar to set the color.
// status bar color
UIView *view = [[UIView alloc] initWithFrame:CGRectMake(0, -20, ScreenWidth, 20)];
[view setBackgroundColor:COLOR_APP_MAIN];
    
 [viewController.navigationController.navigationBar addSubview:view];
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NSDictionary to NSString

// Start
NSDictionary *parametersDic = [NSDictionary dictionaryWithObjectsAndKeys:
                               self.providerStr, KEY_LOGIN_PROVIDER,
                               token, KEY_TOKEN,
                               response, KEY_RESPONSE,
                               nil];

NSData *jsonData = parametersDic == nil ? nil : [NSJSONSerialization dataWithJSONObject:parametersDic options:0 error:nil];
NSString *requestBody = [[NSString alloc] initWithData:jsonData encoding:NSUTF8StringEncoding];
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Convert dictionary to NSData and data to string.

UIButton setImage does not work

If setting image does not take effect.

The enable property of UIButton is NO. Set enable to YES.

37. User-agent Determines the device

UIWebView determines which interface to display based on the user-Agent value. If you want to set it to global, load it directly when the application starts.

- (void)appendUserAgent
{
    NSString *oldAgent = [self.WebView stringByEvaluatingJavaScriptFromString:@"navigator.userAgent"];
    NSString *newAgent = [oldAgent stringByAppendingString:@"iOS"];
    
    NSDictionary *dic = [[NSDictionary alloc] initWithObjectsAndKeys:
                         newAgent, @"UserAgent", nil];
    
    [[NSUserDefaults standardUserDefaults] registerDefaults:dic];
}
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@ “iOS” is the added custom.

UIPasteboard mask paste option

When UIpasteboard string is set to @ “”, then string becomes nil. The paste option will not appear.

Use class_addMethod

When ARC environment

class_addMethod([self class], @selector(resolveThisMethodDynamically), (IMP) myMethodIMP, “v@:”);

If you want to use @selector, you need to use a super class, otherwise you’ll get an error. When MRC environment

class_addMethod([EmptyClass class], @selector(sayHello2), (IMP)sayHello, “v@:”);

I can define it any way I want. However, the system will display a warning, you can ignore the warning.

AFNetworking sends form-data

Convert JSON data to NSData and put it in the body of the Request. Sending it to the server is in form-data format.

41. Attention to non-empty judgment

BOOL hasBccCode = YES;
if ( nil == bccCodeStr
    || [bccCodeStr isKindOfClass:[NSNull class]]
    || [bccCodeStr isEqualToString:@""])
{
    hasBccCode = NO;
}
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If non-null judgment and type judgment are performed, a new type judgment is required and then a non-null judgment is performed; otherwise, the crash will occur.

IOS 8.4 UIAlertView keyboard display problem

You can check whether the keyboard is hidden before you call UIAlertView.

@property (nonatomic, assign) BOOL hasShowdKeyboard;

[[NSNotificationCenter defaultCenter] addObserver:self
                                         selector:@selector(showKeyboard)
                                             name:UIKeyboardWillShowNotification
                                           object:nil];

[[NSNotificationCenter defaultCenter] addObserver:self
                                         selector:@selector(dismissKeyboard)
                                             name:UIKeyboardDidHideNotification
                                           object:nil];

- (void)showKeyboard
{
    self.hasShowdKeyboard = YES;
}

- (void)dismissKeyboard
{
    self.hasShowdKeyboard = NO;
}

while( self.hasShowdKeyboard ) { [[NSRunLoop currentRunLoop] runMode:NSDefaultRunLoopMode beforeDate:[NSDate distantFuture]];  } UIAlertView* alerview = [[UIAlertView alloc] initWithTitle:@"" message:@"Cancel the modification?" delegate:self cancelButtonTitle:@"Cancel" otherButtonTitles: @"Sure", nil];
[alerview show];
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43. Setup of Chinese input method for simulator

The default configuration of the simulator does not have “small Earth” and can only be entered in English. The method of adding Chinese is as follows:

Select Settings– >General–>Keyboard–>International KeyBoards–>Add New Keyboard–>Chinese Simplified(PinYin) That is, we generally use the simplified Chinese pinyin input method, after good configuration, and then input text, click the pop-up keyboard “small earth” can be input Chinese. If not, long press “Small Earth” to select Chinese.

44, iPhone number pad

Phone keyboard type:

  1. The number pad can only enter numbers and cannot switch to other inputs
  2. Phone Pad type: Used for making calls. You can enter numbers and + * #

45. UIView comes with animation flip interface

- (IBAction)changeImages:(id)sender
{
    CGContextRef context = UIGraphicsGetCurrentContext();
    
    [UIView beginAnimations:nil context:context];
    [UIView setAnimationCurve:UIViewAnimationCurveEaseInOut];
    [UIView setAnimationDuration: 1.0]; [UIViewsetAnimationTransition:UIViewAnimationTransitionCurlDown forView:_parentView cache:YES];
    [UIView setAnimationTransition:UIViewAnimationTransitionCurlUp forView:_parentView cache:YES];
    [UIView setAnimationTransition:UIViewAnimationTransitionFlipFromLeft forView:_parentView cache:YES];
    [UIView setAnimationTransition:UIViewAnimationTransitionFlipFromRight forView:_parentView cache:YES];
    
    NSInteger purple = [[_parentView subviews] indexOfObject:self.image1];
    NSInteger maroon = [[_parentView subviews] indexOfObject:self.image2];
    
    [_parentView exchangeSubviewAtIndex:purple withSubviewAtIndex:maroon];
    
    [UIView setAnimationDelegate:self];
    [UIView commitAnimations];
    
    
}
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46. KVO listens for other class variables

[[HXSLocationManager sharedManager] addObserver:self
                                         forKeyPath:@"currentBoxEntry.boxCodeStr"
                                            options:NSKeyValueObservingOptionNew | NSKeyValueObservingOptionInitial | NSKeyValueObservingOptionOld context:nil];
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In the self implementation classes for [HXSLocationManager sharedManager] class variables in @ “currentBoxEntry. BoxCodeStr” listening.

Ios9 Crash animateWithDuration

In iOS9, if you’re doing animateWithDuration, the view is released, you’re going to crash.

[UIView animateWithDuration: 0.25 f animations: ^ {self. Frame = selfFrame;} completion: ^ (BOOL finished) {if(finished) { [super removeFromSuperview]; }}];Copy the code

Will crash.

[UIView animateWithDuration: 0.25 f delay: 0 usingSpringWithDamping: initialSpringVelocity 1.0:1.0 options:UIViewAnimationOptionCurveLinear animations:^{ self.frame = selfFrame;  } completion:^(BOOL finished) { [super removeFromSuperview]; }];Copy the code

Won’t Crash.

Translate URL encoding to NSString

When deleting movies in iPTV project, two parameters, user name and movie ID, need to be transmitted in URL. If the user name contains Chinese characters, the user name cannot be deleted.

In previous tests, the user name bound to the mobile phone number was English or numeric. The problem was discovered when the phone number was tested.

If the URL contains Chinese characters, you need to translate the URL encoding.

urlStr = [urlStr stringByAddingPercentEscapesUsingEncoding:NSUTF8StringEncoding];
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If the lowest version is iOS9, use it

urlStr = [urlStr stringByAddingPercentEncodingWithAllowedCharacters:[NSCharacterSet URLQueryAllowedCharacterSet]];
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Xcode iOS loading images can only be PNG

JPG images can be seen in Xcode, but will fail when loading. Could not load the “ReversalImage1” image referenced from a nib in the bun

PNG images must be used.


Add the suffix if you want to use JPG

[UIImage imageNamed:@"myImage.jpg"];
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50. Save the full screen as image

CGSize imageSize = [[UIScreen mainScreen] bounds].size;
UIGraphicsBeginImageContextWithOptions(imageSize, NO, 0);
CGContextRef context = UIGraphicsGetCurrentContext();

for (UIWindow * window in [[UIApplication sharedApplication] windows]) {
    if(! [window respondsToSelector:@selector(screen)] || [window screen] == [UIScreen mainScreen]) { CGContextSaveGState(context); CGContextTranslateCTM(context, [window center].x, [window center].y); CGContextConcatCTM(context, [window transform]); CGContextTranslateCTM(context, -[window bounds].size.width*[[window layer] anchorPoint].x, -[window bounds].size.height*[[window layer] anchorPoint].y); [[window layer] renderInContext:context]; CGContextRestoreGState(context); } } UIImage *image = UIGraphicsGetImageFromCurrentImageContext(); UIGraphicsEndImageContext();Copy the code

51. Determine the location status locationServicesEnabled

[CLLocationManager locationServicesEnabled] checks the location service switch of the entire iOS system and does not check whether the current app is disabled. through

CLAuthorizationStatus status = [CLLocationManager authorizationStatus];
    if (kCLAuthorizationStatusDenied == status || kCLAuthorizationStatusRestricted == status) {
        [self locationManager:self.locationManager didUpdateLocations:nil];
    } else { // the user has closed this function
        [self.locationManager startUpdatingLocation];
    }
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CLAuthorizationStatus to determine whether GPS can be accessed

52. Pay attention to the size of wechat sharing

The size of text must be greater than 0 and less than 10K

Image must be less than 64K

The URL must be greater than 0K

53. Clearing the image cache

SDWebImage is generally used to display and cache images. Generally, if the content of the cache is too much, the cache needs to be cleared

When clearing SDWebImage’s memory and hard disk, you can clear session and cookie caches at the same time.

// clearMemory [[SDImageCache sharedImageCache] clearMemory]; NSHTTPCookieStorage *storage = [NSHTTPCookieStorage sharedHTTPCookieStorage];for (NSHTTPCookie *cookie in[storage cookies]) { [storage deleteCookie:cookie]; } NSURLSessionConfiguration *config = [NSURLSessionConfiguration defaultSessionConfiguration]; [config.URLCache removeAllCachedResponses]; [[NSURLCache sharedURLCache] removeAllCachedResponses]; / / clean up hard drive [[SDImageCache sharedImageCache] clearDiskOnCompletion: ^ {[MBProgressHUD hideAllHUDsForView: self. The view animated:YES]; [self.tableView reloadData]; }];Copy the code

TableView Header View scroll with TableView

When the TableView type is plain, the header View will stay at the top.

When it’s group, the header view will scroll along with the TableView.

55. TabBar title setting

Tabbars can be set in xiB or storyboard

1. Self. NavigationItem. Title set navigation title need to use the set.

2. Self. title in TAB bar main VC setting self.title causes navigation title to be changed along with TAB bar title.

UITabBar, remove the shadow at the top

Add these two lines of code:

[[UITabBar appearance] setShadowImage:[[UIImage alloc] init]];
[[UITabBar appearance] setBackgroundImage:[[UIImage alloc] init]];
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The top shadow is on UIWindow, so it can’t be easily set to go away.

57. When in a row, multiple UIKits are dynamic width Settings

58. JSON ‘ ‘converts to nil

When using AFNetworking, use

AFJSONResponseSerializer *response = [[AFJSONResponseSerializer alloc] init];
response.removesKeysWithNullValues = YES;
       
_sharedClient.responseSerializer = response;
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This parameter removesKeysWithNullValues null values can be deleted, then the Value is nil

// END