how to use cancelPreviousPerformRequestsWithTarget

问题

I have a method in scrollView:didScroll like this:

[self.navigationCollectionView moveWhiteLineToPointX:middleX WithWidth:middleWidth animated:NO];

I don't want this method be called multiple times if user is scrolling fast, so I want to use +cancelPreviousPerformRequestsWithTarget:selector:object

+ (void)cancelPreviousPerformRequestsWithTarget:(id)aTarget selector:(SEL)aSelector object:(id)anArgument

I don't know how to feed the correct parameters for this API, especially for the target and the argument. Could someone help?

回答1:

try this

[[self class] cancelPreviousPerformRequestsWithTarget:self selector:@selector(scrollViewDidScroll:) object:nil];

回答2:

For canceling:

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

And for calling perform selector:

[self performSelector:@selector(yourSelectorFunction) withObject:nil afterDelay:0.4];

来源：https://stackoverflow.com/questions/30100259/how-to-use-cancelpreviousperformrequestswithtarget