IOS 关于取消延迟执行函数的种种。performSelector与cancelPreviousPerformRequestsWithTarget-优快云博客

本文链接：https://blog.youkuaiyun.com/samuelltk/article/details/8994313

本文深入探讨了Objective-C中NSInvocation类的使用方式，特别是如何进行延迟执行及其对应的取消方法。通过实例分析，展示了带参数与无参数情况下的不同行为，并提供了代码示例和下载链接。

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@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：

    [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：

    [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。

代码下载地址：http://download.youkuaiyun.com/detail/samuelltk/5481327