通过NSTimer看IPhone对@selector的函数如何传参数

NSMutableDictionary *dict = [[NSMutableDictionary alloc] init];  

    if(oldView != nil)

    {

        [dict setObject:oldView forKey:@"oldView"]; 

    }

    if(newView != nil)

    {

        [dict setObject:newView forKey:@"newView"]; 

    } 

    [NSTimer scheduledTimerWithTimeInterval:0.0 target:self selector:@selector(onTimer:) userInfo:dict repeats:NO];  

    [dict release];

- (void)onTimer:(NSTimer *)timer 

{  

    UIView *oldView = [[timer userInfo] objectForKey:@"oldView"];

    UIView *newView = [[timer userInfo] objectForKey:@"newView"];  

    [UIView animateWithDuration:2.0  delay:0

                        options:UIViewAnimationOptionAllowUserInteraction

                     animations:^{  

                         oldView.alpha = 0.0; 

                         newView.alpha = 1.0;  

                     }  

} 

从上可以看出，NSTimer在对@selector(onTimer:)传递参数时，将传参的对象储存在了NSTimer的userInfo的字典里，在- (void)onTimer:(NSTimer *)timer中

通过取出该字典加以使用。

这个其实也就是iphone对@selector对象传参的通用的形式。