iOS7 iOS8 毛玻璃效果的分别实现

[_headBGIV sd_setImageWithURL:headIVURL
completed:^(UIImage *image, NSError *error, SDImageCacheType cacheType, NSURL *imageURL) {
if (IOS8_OR_LATER)
{
UIBlurEffect *blur = [UIBlurEffect effectWithStyle:UIBlurEffectStyleDark];
UIVisualEffectView *effectview = [[UIVisualEffectView alloc] initWithEffect:blur];
effectview.frame = _headBGIV.bounds;
[_headBGIV addSubview:effectview];
}
else
{
_headBGIV.image = [image applyDarkEffect];
}

// 动画显示
NSString *aniType = kCATransitionFade;
CATransition *fadeAni = [CATransition animation];
fadeAni.duration = 0.68f;
fadeAni.type = aniType;
fadeAni.timingFunction = [CAMediaTimingFunction functionWithName:kCAMediaTimingFunctionEaseInEaseOut];
[[headView layer] addAnimation:fadeAni forKey:nil];
}];