问题描述
我有一个 UIButton 可以在突出显示时更改图像.从 UIControlStateHighlight 过渡到 UIControlStateNormal 时,我希望突出显示的图像慢慢淡入正常图像.是否有捷径可寻?
I have a UIButton that changes image on highlight. When transitioning from UIControlStateHighlight to UIControlStateNormal, I want the highlighted image to slowly fade back into the normal image. Is there an easy way to do this?
推荐答案
我最终继承了 UIButton.这是实现文件代码.我取出了一些特定于应用程序的东西,所以我没有测试过这个确切的代码,但应该没问题:
I ended up subclassing UIButton. Here's the implementation file code. I took some app-specific stuff out, so I haven't tested this exact code, but it should be fine:
#import "SlowFadeButton.h"
@interface SlowFadeButton ()
@property(strong, nonatomic)UIImageView *glowOverlayImgView; // Used to overlay glowing animal image and fade out
@end
@implementation SlowFadeButton
-(id)initWithFrame:(CGRect)theFrame mainImg:(UIImage*)theMainImg highlightImg:(UIImage*)theHighlightImg
{
if((self = [SlowFadeButton buttonWithType:UIButtonTypeCustom])) {
self.frame = theFrame;
if(!theMainImg) {
NSLog(@"Problem loading the main image
");
}
else if(!theHighlightImg) {
NSLog(@"Problem loading the highlight image
");
}
[self setImage:theMainImg forState:UIControlStateNormal];
self.glowOverlayImgView = [[UIImageView alloc] initWithImage:theHighlightImg];
self.glowOverlayImgView.frame = self.imageView.frame;
self.glowOverlayImgView.bounds = self.imageView.bounds;
self.adjustsImageWhenHighlighted = NO;
}
return self;
}
-(void)setHighlighted:(BOOL)highlighted
{
// Check if button is going from not highlighted to highlighted
if(![self isHighlighted] && highlighted) {
self.glowOverlayImgView.alpha = 1;
[self addSubview:self.glowOverlayImgView];
}
// Check if button is going from highlighted to not highlighted
else if([self isHighlighted] && !highlighted) {
[UIView animateWithDuration:1.0f
animations:^{
self.glowOverlayImgView.alpha = 0;
}
completion:NULL];
}
[super setHighlighted:highlighted];
}
-(void)setGlowOverlayImgView:(UIImageView *)glowOverlayImgView
{
if(glowOverlayImgView != _glowOverlayImgView) {
_glowOverlayImgView = glowOverlayImgView;
}
self.glowOverlayImgView.alpha = 0;
}
@end
您也可以从 [self imageForState:UIControlStateHighlighted]
中提取突出显示的图像并使用它,它应该可以正常工作.主要是确保adjustsImageWhenHighlighted = NO
,然后重写setHighlighted:
方法.
You could also just pull the highlighted image from [self imageForState:UIControlStateHighlighted]
and use that, it should work the same. The main things are to make sure adjustsImageWhenHighlighted = NO
, and then overriding the setHighlighted:
method.
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