IOS 关于取消延迟执行函数的种种。performSelector与cancelPreviousPerformRequestsWithTarget

本文非本人撰写

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1. @interface NSObject (NSDelayedPerforming)
2. - (void)performSelector:(SEL)aSelector withObject:(id)anArgument afterDelay:(NSTimeInterval)delay inModes:(NSArray *)modes;
3. - (void)performSelector:(SEL)aSelector withObject:(id)anArgument afterDelay:(NSTimeInterval)delay;
4. + (void)cancelPreviousPerformRequestsWithTarget:(id)aTarget selector:(SEL)aSelector object:(id)anArgument;
5. + (void)cancelPreviousPerformRequestsWithTarget:(id)aTarget;
6. @end

最近看到大家对cancelPreviousPerformRequestsWithTarget不能取消带参数的
- (void)performSelector:(SEL)aSelector withObject:(id)anArgument afterDelay:(NSTimeInterval)delay;
情况，写了一点点代码调试了一下，发现如果是带参数，那取消时的参数也要一致，否则不能取消成功。
开始延迟执行：

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

假如在三秒内执行以下取消方法，则结果分别为：

[cpp] view plaincopy

1. [NSObject cancelPreviousPerformRequestsWithTarget:self selector:@selector(didRuninCurrModel:) object:[NSNumber numberWithBool:YES]];//可以取消成功。
2. [NSObject cancelPreviousPerformRequestsWithTarget:self selector:@selector(didRuninCurrModel:) object:[NSNumber numberWithBool:NO]];//不能取消成功。参数不匹配
3. [NSObject cancelPreviousPerformRequestsWithTarget:self selector:@selector(didRuninCurrModel:) object:nil];//不能取消成功。参数不匹配
4. [NSObject cancelPreviousPerformRequestsWithTarget:self selector:@selector(didRuninCurrModelNoArgument) object:nil];//可以成功取消
5. [NSObject cancelPreviousPerformRequestsWithTarget:self];//可以成功取消全部。
6. [[self class] cancelPreviousPerformRequestsWithTarget:self];//可以成功取消全部。

代码下载地址：http://download.csdn.net/detail/samuelltk/5481327