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

最新推荐文章于 2015-12-29 17:48:52 发布

转载最新推荐文章于 2015-12-29 17:48:52 发布 · 85 阅读

本文探讨了Objective-C中使用NSObject扩展方法实现延迟执行功能，并详细介绍了如何通过匹配选择器和参数来正确取消延迟执行的任务。

摘要生成于 C知道，由 DeepSeek-R1 满血版支持，前往体验 >

本文非本人撰写

[cpp] view plain copy

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

[cpp] view plain copy

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

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