RunloopListen.h

#import <Foundation/Foundation.h>NS_ASSUME_NONNULL_BEGIN@interface RunloopListen : NSObject+ (void)listen;@endNS_ASSUME_NONNULL_END

RunloopListen.m

#import "RunloopListen.h"@implementation RunloopListen+ (void)listen{CFRunLoopObserverContext context = {0, (__bridge void *)(self), NULL, NULL, NULL};CFRunLoopObserverRef observer = CFRunLoopObserverCreate(kCFAllocatorDefault, kCFRunLoopAllActivities, YES, 0, &myRunLoopObserver, &context);NSRunLoop *myRunLoop = [NSRunLoop currentRunLoop];CFRunLoopRef cfRunLoop = [myRunLoop getCFRunLoop];CFRunLoopAddObserver(cfRunLoop, observer, kCFRunLoopDefaultMode);
}void myRunLoopObserver(CFRunLoopObserverRef observer, CFRunLoopActivity activity, void *info)
{switch(activity){case kCFRunLoopEntry:NSLog(@"run loop entry");break;case kCFRunLoopBeforeTimers:NSLog(@"run loop before timers");break;case kCFRunLoopBeforeSources:NSLog(@"run loop before sources");break;case kCFRunLoopBeforeWaiting:NSLog(@"run loop before waiting -----------------------");break;case kCFRunLoopAfterWaiting:NSLog(@"run loop after waiting -----------------------");break;case kCFRunLoopExit:NSLog(@"run loop exit");break;default:break;}
}@end

在swift项目中使用

参考博客

iOS viewDidLoad 中创建的局部变量释放时机