ios - 错误 : The file. ..在 imageData 上调用 writeToFile 时不存在

Question

我正在尝试在 NSURLSessionDownloadTask 的完成 block 中使用以下代码将数据写入文件:

   void (^completionBlock)(NSURLResponse *response, NSURL *filePath, NSError *error) = ^void (NSURLResponse *response, NSURL *filePath, NSError *error) {
        dispatch_async(dispatch_get_main_queue(), ^{
            if (!error){
                NSData *imageData = [NSData dataWithContentsOfURL:filePath];
                if(imageData) NSLog(@"image is not null");

                if(pic == 1) self.imageView.image = [UIImage imageWithData:imageData];
                else if(pic==2) self.imageView2.image = [UIImage imageWithData:imageData];

                NSArray *paths = [[NSFileManager defaultManager] URLsForDirectory:NSDocumentDirectory inDomains:NSUserDomainMask];
                NSURL *documentsDirectoryURL = [paths lastObject];
                NSURL *saveLocation;
                if(pic == 1) saveLocation = [documentsDirectoryURL URLByAppendingPathComponent:self.pictureName1];
                else if (pic == 2) saveLocation = [documentsDirectoryURL URLByAppendingPathComponent:self.pictureName2];
                else saveLocation = [documentsDirectoryURL URLByAppendingPathComponent:self.pictureName3];

                NSLog(@"for # %d writing to file %@", pic, saveLocation);

                NSError *error = nil;                
                [imageData writeToFile:[saveLocation absoluteString] options:NSAtomicWrite error: &error];
                if(error){
                    NSLog(@"FAILED\n\n\n %@ \n\n\n", [error description]);
                }
     }

我能够在 UIImageViews 中显示下载的图像，并且我对 imageData 的空检查同样确认它不为空。但是，当我尝试将数据写入文件时，我的 NSLog 打印出以下错误，表明写入失败:

(log statements)
# 3 writing to file file:///var/mobile/Containers/Data/Application/3743A163-7EE1-4A5A-BF81-7D1344D6DA45/Documents/pic3.png
Error Domain=NSCocoaErrorDomain Code=4 "The file “pic1.jpg” doesn’t exist." 
UserInfo={NSFilePath=file:///var/mobile/Containers/Data/Application/3743A163-7EE1-
4A5A-BF81-7D1344D6DA45/Documents/pic1.jpg, NSUnderlyingError=0x16d67200 {Error
Domain=NSPOSIXErrorDomain Code=2 "No such file or directory"}} 

我没能在 SO 上找到另一个问题，指出此文件的此错误消息，而且我发现错误消息非常违反直觉。我的错误在哪里？

Answer 1

使用 [saveLocation path] 代替 [saveLocation absoluteString]。基本上前者给你“file:///path/filename”，而后者给你“/path/filename”，这是正确的格式。