在 Xcode 中,当我尝试将超过 5 张图片 添加到我的库时,出现以下错误:
Error Domain=ALAssetsLibraryErrorDomain Code=-3301 "Write busy" UserInfo=0xa706aa0 {NSLocalizedRecoverySuggestion=Try to write again, NSLocalizedFailureReason=There was a problem writing this asset because the writing resources are busy., NSLocalizedDescription=Write busy, NSUnderlyingError=0xa770110 "Write busy"}
为了解决这个问题,我发现线程可以解决我的问题。文档指出我可以使用 POSIX 线程或 NSThreads
。当我尝试使用 POSIX 线程时,我将我的线程设置为可连接,并且我正在创建一个 void * 函数:
void * myFunc (void * image)
{
UIImageWriteToSavedPhotosAlbum((__bridge UIImage *)(image),self,nil,nil);
pthread_exit(NULL);
return NULL;
}
我也在等线程结束。但是仍然只写了5张图片。
我试过使用 NSThreads
并做了:
[self performSelectorOnMainThread:@selector(myFunc:) withObject:image waitUntilDone:YES];
但是还是不行。
我的问题有答案吗?这对我的工作至关重要。
谢谢。
编辑:
也尝试过 dispatch_async。有错吗?
dispatch_queue_t myQueue = dispatch_queue_create("com.cropr.myqueue", 0);
for (UIImage * image in images) {
dispatch_async(myQueue, ^{
[self.library saveImage:image toAlbum:@"Cropr" withCompletionBlock:^(NSError *error) {
if (error!=nil) {
NSLog(@"Big error: %@", [error description]);
}
}];
});
}
我需要添加什么?
最佳答案
您可以尝试随后 写入所有图像,而不是同时。以下代码利用 ALAssetsLibrary
,并实现了一个“异步循环”,它按顺序调用许多异步方法。
typedef void (^completion_t)(id result);
- (void) writeImages:(NSMutableArray*)images
completion:(completion_t)completionHandler {
if ([images count] == 0) {
if (completionHandler) {
// Signal completion to the call-site. Use an appropriate result,
// instead of @"finished" possibly pass an array of URLs and NSErrors
// generated below in "handle URL or error".
completionHandler(@"finished");
}
return;
}
UIImage* image = [images firstObject];
[images removeObjectAtIndex:0];
[self.assetsLibrary writeImageToSavedPhotosAlbum:image.CGImage
orientation:ALAssetOrientationUp
completionBlock:^(NSURL *assetURL, NSError *error)
{
// Caution: check the execution context - it may be any thread,
// possibly use dispatch_async to dispatch to the main thread or
// any other queue.
// handle URL or error
...
// next image:
[self writeImages:images completion:completionHandler];
}];
}
用法:
[foo writeImages:[foo.images mutableCopy] completion:^(id result){
// Caution: check the execution context - it may be any thread
NSLog(@"Result: %@", result);
}];
关于ios编程: Using threads to add multiple images to library,我们在Stack Overflow上找到一个类似的问题: https://stackoverflow.com/questions/20662908/