让 performSelector:withObject:aft

业务中有些场景需要做延时处理，一般采用的是 dispatch_after 这个 GCD 方法来实现，但是缺点是这种延时没办法取消，于是乎有了：

[self performSelector:@selector(myDelayedMethod) withObject: self afterDelay: desiredDelay];

[NSObject cancelPreviousPerformRequestsWithTarget: self selector:@selector(myDelayedMethod) object: self];

用了上面的方法，可以随时取消还没有执行的延时，但这个 API 只支持一个参数，有时候并不能满足我们的要求，网上搜索都提到了用 NSInvocation 或者 dispatch_after代替，但是这些方法都存在不能延时或者不能取消的问题，
于是试给 NSObject 扩展一下，让其支持多个参数，并支持 cancelPreviousPerformRequestsWithTarget 取消，原理其实很简单，直接贴代码：

NSObject+Additions.h

@interface NSObject (Additions)

- (void)performSelector:(SEL)aSelector withObject:(id)argument0 withObject:(id)argument1 afterDelay:(NSTimeInterval)delay;

- (void)performSelector:(SEL)aSelector withObject:(id)argument0 withObject:(id)argument1 afterDelay:(NSTimeInterval)delay inModes:(NSArray<NSRunLoopMode> *)modes;

+ (void)cancelPreviousPerformRequestsWithTarget:(id)aTarget selector:(SEL)aSelector object:(id)argument0 object:(id)argument1;

@end

NSObject+Additions.m

@implementation NSObject (Additions)

- (void)performSelector:(SEL)aSelector withObject:(id)argument0 withObject:(id)argument1 afterDelay:(NSTimeInterval)delay {
    
    [self performSelector:aSelector withObject:argument0 withObject:argument1 afterDelay:delay inModes:@[NSDefaultRunLoopMode]];
}

- (void)performSelector:(SEL)aSelector withObject:(id)argument0 withObject:(id)argument1 afterDelay:(NSTimeInterval)delay inModes:(NSArray<NSRunLoopMode> *)modes {
    NSArray *arguments = [NSArray arrayWithObjects:NSStringFromSelector(aSelector), argument0, argument1, nil];
    
    [self performSelector:@selector(_performWithArguments:) withObject:arguments afterDelay:delay inModes:modes];
}


+ (void)cancelPreviousPerformRequestsWithTarget:(id)aTarget selector:(SEL)aSelector object:(id)argument0 object:(id)argument1 {
    
    NSArray *arguments = [NSArray arrayWithObjects:NSStringFromSelector(aSelector), argument0, argument1, nil];
    
    [self cancelPreviousPerformRequestsWithTarget:aTarget selector:@selector(_performWithArguments:) object:arguments];
}

- (void)_performWithArguments:(NSArray *)arguments {
    
    SEL aSelector = NSSelectorFromString([arguments firstObject]);
    
    NSMethodSignature *signature = [self methodSignatureForSelector:aSelector];
    NSInvocation *invocation = [NSInvocation invocationWithMethodSignature:signature];
    [invocation setTarget:self];
    [invocation setSelector:aSelector];
    
    for (NSUInteger i = 1; i < arguments.count; i++) {
        id obj = arguments[i];
        [invocation setArgument:&obj atIndex:i + 1];
    }
    
    [invocation invoke];
}

@end