在调用 removeFromSuperview 的时候，当前视图会突然消失,这样显得很不友好。这段代码能够让视图慢慢消失。

gistfile1.m

//
//  UIView+JTRemoveAnimated.h
//
//  Created by james on 9/1/11.
//  http://ioscodesnippet.tumblr.com/
//
@interface UIView (JTRemoveAnimated)
 
- (void)removeFromSuperviewAnimated;
 
@end
 
 
//
//  UIView+JTRemoveAnimated.m
//
//  Created by james on 9/1/11.
//  http://ioscodesnippet.tumblr.com/
//
#import <quartzcore quartzcore.h="">
 
@implementation UIView (JTRemoveAnimated)
 
// remove static analyser warnings
#ifndef __clang_analyzer__
 
- (void)animationDidStop:(NSString *)animationID finished:(NSNumber *)finished context:(void *)context {
    if ([animationID isEqualToString:@"fadeout"]) {
        // Restore the opacity
        CGFloat originalOpacity = [(NSNumber *)context floatValue];
        self.layer.opacity = originalOpacity;
        [self removeFromSuperview];
        [(NSNumber *)context release];
    }
}
 
- (void)removeFromSuperviewAnimated {
    [UIView beginAnimations:@"fadeout" context:[[NSNumber numberWithFloat:self.layer.opacity] retain]];
    [UIView setAnimationDuration:0.3];
    [UIView setAnimationDidStopSelector:@selector(animationDidStop:finished:context:)];
    [UIView setAnimationDelegate:self];
    self.layer.opacity = 0;
    [UIView commitAnimations];
}
 
#endif
 
@end