Knowledge summary

  • One, the foundation

One, the foundation

  1. How does Runloop relate to threads?

  2. When will the automatic release pool be released?

  3. What is the difference between the weak keyword and assign?

  4. How to use the copy keyword?

  5. @property(copy) NSMutableArray * array; What’s the problem with writing this?

  6. How do I get my classes to use the copy modifier? That is, make the object you write copy, right?

  7. What is the nature of @property? How do ivar, getters, setters get generated and added to this class?

  8. multithreading

  9. How do you use @property in @protocol and category?

  10. What attribute keywords are in @ Property?

  11. Does the weak property need to be nil in dealloc?

  12. What does @synthesize and @dynamic do?

  13. In ARC, what are the default keywords that are not displayed when specifying any attribute keywords?

  14. Nsstrings (or NSArray,NSDictionary) declared with @property often use the copy keyword. Why? What problems might arise if you use the strong keyword instead?

  15. What are the rules for @synthesize instance variables? If the property name is foo and there is an instance variable named _foo, will the new variable be synthesized automatically?

  16. After you have the automatic synthesize property instance variable, what are the scenarios for @synthesize?

  17. What would objC send if it wanted to send a nil object?

  18. What is the direct relationship between objC sending an object [obj foo] and objc_msgSend()?

  19. When is an exception to an unrecognized selector included?

  20. How is memory laid out for an ObjC object? (Consider the parent class)

  21. What does an ISA pointer to an objC object point to? What does it do?

  22. How does runtime find the corresponding IMP address by selector? (Consider class and instance methods respectively)

  23. What does the following code output?

  24. Do objects associated with the Runtime Associate method need to be released when the main object is dealloc?

  25. What are the essential differences and connections between class methods and instance methods in OBJC?

  26. What does the _objc_msgForward function do, and what happens when you call it directly?

  27. How does runtime implement automatic nil for weak variables?

  28. Can I add instance variables to the compiled class? Can you add instance variables to a class that you want to create? Why is that?

  29. What does runloop have to do with threads?

  30. What is the mode of runloop?

  31. With + scheduledTimerWithTimeInterval… When sliding the list on the page, the timer will pause the callback. Why? How to solve it?

  32. Guess how runloop is implemented internally?

  33. What mechanism does ObjC use to manage object memory?

  34. In what ways does ARC help developers manage memory?

  35. When does BAD_ACCESS occur?

  36. When can reference loops occur using blocks and how can they be resolved?

  37. How do I modify external block variables inside a block?

  38. Apple is the symbol implementation of autoreleasepool?

  39. At what point does an AutoRelease object get released without manually knowing the AutoReleasepool? (such as in a VC viewDidLoad)

  40. Are reference loops also considered when using some of your blocak apis (such as the block version of UIView when writing animations)?

  41. What are the two types of DISPATch_queue_t GCD queues?

  42. How do I synchronize several asynchronous calls with GCD? (For example, load multiple images asynchronously based on several urls, and then compose a whole image after downloading them all)

  43. What does dispatch_barrier_async do?

  44. Why did Apple disable dispatch_get_current_queue?

  45. How does the following code run?Only: 1 is printed. The sending main thread is locked.

  46. AddObserver: forKeyPath: options: context: what are the effect of various parameters, which need to implement in the observer method to obtain KVO callback?

  47. How do I manually trigger a value’s KVO?

  48. If a class has an instance variable NSString * _foo, can setValue:forKey: be called with foo or _foo as the key?

  49. How is the set operator in KVC’s keyPath used?

  50. Must the keyPath of KVC and KVO be attributes?

  51. How do I turn off the default implementation of the default KVO and enter the custom KVO implementation?

  52. How does Apple implement KVO for an object?

  53. Why can the view property connected by IBOutlet be set to weak?

  54. How to use User Defined Runtime Attributes in IB?

  55. How do I debug BAD_ACCESS errors?

  56. Common LLDB (GDB) debugging commands?

  57. IOS is prone to several scenarios of “circular reference”

  58. What’s the difference between load and initialized?

  59. HTTP and HTTPS

  60. Common Exception types

  61. The Category and the Extension

  62. Responder chain

  63. The optimization of UITableView

  64. Off-screen Render

  65. UIView and CALayer

  66. TCP and UDP

  67. The socket and HTTP

  68. Remote push APNS

  69. IOS application life cycle

  70. View View life cycle

  71. autorelease pool

  72. view layout

  73. Application architecture MVC, MVVM

  74. FMDB,SQLite

  75. This section describes memory partitions

  76. Function of each attribute

  77. Brief Notification, KVC KVO, delegate? The difference between them?

  78. What do ID and nil stand for

  79. nil,Nil,NULL, NSNull

  80. What does sending a message to a nil object send?

  81. Self. And self->

  82. How do I access and modify private attributes of a class

  83. How do I define a property for class that is read only externally but read and write internally

  84. What does meta-class mean in OC?

  85. NSString uses the difference between copy and strong

  86. The steps to create an object

  87. setter,getter

  88. Id, instanceType, what’s the difference?

  89. Memory management

  90. The underlying implementation of KVC?

  91. Block memory management

  92. The startup process of App starts from Main

  93. How do I nest a CollectionView inside a TableView cell

  94. AwakeFromNib versus viewDidLoad

  95. A common Crash scenario

  96. AFN Resumable data

  97. Client caching mechanism

  98. Data storage mode

  99. The App needs to load a large amount of data and send requests to the server, but the server is stuck. How to solve the problem?

  100. How to solve the problem of repeated requests for the same network address in network image processing?

  101. How do I synchronize several asynchronous calls with GCD? (For example, load multiple images asynchronously based on several urls, and then compose a whole image after downloading them all)

  102. The difference between NSOperation, CGD, NSThread

  103. Whether you can place time-consuming operations in the NSNotificationCenter

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