IOS App startup optimization (I) : Detect startup time

IOS App startup Optimization (2) : Physical memory and virtual memory

IOS App startup optimization (3) : binary rearrangement

IOS App startup optimization (4) : pile && get method symbol at compile time

IOS App startup optimization (5) : Collect symbols && generate Order File

IOS App launch optimization (vi) : Utility party directly see here

Effect of contrast

Before optimization

The optimized

Step 1: Add the Build Setting

Target -> Build Setting -> Custom Complier Flags ->

Other C Flags Added

  • -fsanitize-coverage=func,trace-pc-guard

Other Swift Flags Added

  • -sanitize-coverage=func
  • -sanitize=undefined

Step 2: Add code

Add it to the ViewController that started the first time.

#import "dlfcn.h"
#import <libkern/OSAtomic.h>
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void __sanitizer_cov_trace_pc_guard_init(uint32_t *start, uint32_t *stop) {
     static uint64_t N;  // Counter for the guards.
     if (start == stop || *start) return;  // Initialize only once.
     printf("INIT: %p %p\n", start, stop);
     for(uint32_t *x = start; x < stop; x++) *x = ++N; Guards should start from 1.} static OSQueueHead list = OS_ATOMIC_QUEUE_INIT; Typedef struct {void * PC; // save the obtained PC void *next; // point to the next Node} Node; void __sanitizer_cov_trace_pc_guard(uint32_t *guard) { void *PC = __builtin_return_address(0); Node *node = malloc(sizeof(Node)); *node = (Node){PC, NULL}; OSAtomicEnqueue(&list, node, offsetof(node, next)); } - (void)touchesBegan:(NSSet<UITouch *> *)touches withEvent:(UIEvent *)event { NSMutableArray *arr = [NSMutableArray array];whileOSAtomicEnqueue(&list, offsetof(Node, next)); // Exit mechanismif (node == NULL) {
             break; } // get function information Dl_info info; dladdr(node->pc, &info); NSString *sname = [NSString stringWithCString:info.dli_sname encoding:NSUTF8StringEncoding];printf("%s \n", info.dli_sname); BOOL isObjc = [sname hasPrefix:@"+ ["] || [sname hasPrefix:@"-"]; Sname = isObjc? sname: [@"_"stringByAppendingString:sname]; / / to heavyif(! [arr insersobject :sname]) {arr insertObject:sname atIndex:0]; [arr insertObject:sname atIndex:0]; [arr removeObject:[NSString stringWithFormat:@]"%s",__FUNCTION__]]; / / string array synthesis nsstrings * funcStr = [arr componentsJoinedByString: @"\n"]; / / write file nsstrings * filePath = [NSTemporaryDirectory () stringByAppendingPathComponent: @"link.order"];
     NSData * fileContents = [funcStr dataUsingEncoding:NSUTF8StringEncoding];
     NSLog(@"% @", filePath);
     [[NSFileManager defaultManager] createFileAtPath:filePath contents:fileContents attributes:nil];
}
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Step 3: Fetch the Order File

  • The code in Step twoNSLog(@"%@", filePath);The breakpoint
  • If the page doesn’t trigger a click,viewDidLoadIt callstouchesBegan:withEvent:Can also be
  • Record after running the codelink.orderThe path of the
  • FinderAccess pathorder file

Step 4: Set the order file

  • thelink.orderTo the project root directory
  • Target -> Build Setting -> Linking -> Order FileSet the path

Step 5: Compile the code

  • The first steporder fileSetting restore
  • Delete the code added in step 2
  • cleanLater compiled code