使用SDWebImage实现滚动时图片淡入淡出的效果

AFNetworking最大请求的数据量不超过1024KB

在SDWebImage的这个方法中加入以下的代码

- (void)sd_setImageWithURL:(NSURL *)url placeholderImage:(UIImage *)placeholder options:(SDWebImageOptions)options progress:(SDWebImageDownloaderProgressBlock)progressBlock completed:(SDWebImageCompletionBlock)completedBlock {    [self sd_cancelCurrentImageLoad];    objc_setAssociatedObject(self, &imageURLKey, url, OBJC_ASSOCIATION_RETAIN_NONATOMIC);    if (!(options & SDWebImageDelayPlaceholder)) {        dispatch_main_async_safe(^{            self.image = placeholder;        });    }        if (url) {        // check if activityView is enabled or not        if ([self showActivityIndicatorView]) {            [self addActivityIndicator];        }        __weak __typeof(self)wself = self;        idoperation = [SDWebImageManager.sharedManager downloadImageWithURL:url options:options progress:progressBlock completed:^(UIImage *image, NSError *error, SDImageCacheType cacheType, BOOL finished, NSURL *imageURL) {

[wself removeActivityIndicator];

if (!wself) return;

dispatch_main_sync_safe(^{

if (!wself) return;

if (image && (options & SDWebImageAvoidAutoSetImage) && completedBlock)

{

completedBlock(image, error, cacheType, url);

return;

}

#warning 成功请求到图片的时候---此处是加入的代码

else if (image) {

//                    wself.image = image;  原来的判断内的实现 改成

CATransition *transition = [CATransition animation];

transition.type = kCATransitionFade;

transition.duration = 3.0f;

transition.timingFunction = [CAMediaTimingFunction functionWithName:kCAMediaTimingFunctionEaseInEaseOut];

[self.layer addAnimation:transition forKey:nil];

wself.image = image;

[wself setNeedsLayout];

} else {

if ((options & SDWebImageDelayPlaceholder)) {

wself.image = placeholder;

[wself setNeedsLayout];

}

}

if (completedBlock && finished) {

completedBlock(image, error, cacheType, url);

}

});

}];

[self sd_setImageLoadOperation:operation forKey:@"UIImageViewImageLoad"];

} else {

dispatch_main_async_safe(^{

[self removeActivityIndicator];

NSError *error = [NSError errorWithDomain:SDWebImageErrorDomain code:-1 userInfo:@{NSLocalizedDescriptionKey : @"Trying to load a nil url"}];

if (completedBlock) {

completedBlock(nil, error, SDImageCacheTypeNone, url);

}

});

}

}

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