iOS 取消延迟执行的代码

/****************   Delayed perform  ******************/

@interface NSObject (NSDelayedPerforming)

- (void)performSelector:(SEL)aSelector withObject:(nullable id)anArgument afterDelay:(NSTimeInterval)delay inModes:(NSArray *)modes;
- (void)performSelector:(SEL)aSelector withObject:(nullable id)anArgument afterDelay:(NSTimeInterval)delay;
+ (void)cancelPreviousPerformRequestsWithTarget:(id)aTarget selector:(SEL)aSelector object:(nullable id)anArgument;
+ (void)cancelPreviousPerformRequestsWithTarget:(id)aTarget;

@end

@interface NSRunLoop (NSOrderedPerform)

- (void)performSelector:(SEL)aSelector target:(id)target argument:(nullable id)arg order:(NSUInteger)order modes:(NSArray *)modes;
- (void)cancelPerformSelector:(SEL)aSelector target:(id)target argument:(nullable id)arg;
- (void)cancelPerformSelectorsWithTarget:(id)target;

@end

上面是apple提供的延时执行的方法

延迟执行方法：

[self performSelector:@selector(didRuninCurrModel:) withObject:[NSNumber numberWithBool:YES] afterDelay:3.0f];
[self performSelector:@selector(didRuninCurrModelNoArgument) withObject:nil afterDelay:3.0f];

需要注意的是参数的一致性，如下面的取消无法实现：

[NSObject cancelPreviousPerformRequestsWithTarget:self selector:@selector(didRuninCurrModel:) object:[NSNumber numberWithBool:NO]];
[NSObject cancelPreviousPerformRequestsWithTarget:self selector:@selector(didRuninCurrModel:) object:nil];

下面方法可以一次取消所有的延迟执行：

[NSObject cancelPreviousPerformRequestsWithTarget:self];
[[self class] cancelPreviousPerformRequestsWithTarget:self];