照片选取完成过程是异步进行,使用信号量阻塞这个过程。
ALAssetsLibrary *assetsLibrary = [[ALAssetsLibrary alloc] init];
// @weakify(assetsLibrary);
// 创建 一个信号量
dispatch_semaphore_t sema = dispatch_semaphore_create(0);
for (NSURL *assetUrl in selectedAssetURLs) {
dispatch_async(dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT,0), ^{
//NCLog(@"%@",@"处理 多张照片");
[assetsLibrary assetForURL:assetUrl resultBlock:^(ALAsset *asset) {
if (asset) {
UserAlbum *albumImg = [[UserAlbum alloc] init];
albumImg.uploadState = UserAlbumImageUploadStateInit;
UIImage *highQualityImage = [UIImage fullScreenImageALAsset:asset];
UIImage *thumbnailImage = [UIImage imageWithCGImage:[asset thumbnail]];
albumImg.image = highQualityImage;
albumImg.thumbnailImage = thumbnailImage;
[self.images addObject:albumImg];
}
//信号量 通知 +1
dispatch_semaphore_signal(sema);
} failureBlock:^(NSError *error) {
dispatch_semaphore_signal(sema);
}];
});
//dispatch_semaphore_wait(sema, DISPATCH_TIME_FOREVER);
}
//阻塞进程 直到 图片处理完毕
dispatch_semaphore_wait(sema, DISPATCH_TIME_FOREVER);
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。你还可以使用@
来通知其他用户。