iOS 照片扩展 finishContentEditing WithCompletionHandler：无法保存更改

Question

我的照片扩展应用程序可以访问相机和照片。一切正常，但按完成时，无法保存图像。

标准完成处理程序代码：

- (void)finishContentEditingWithCompletionHandler:(void (^)(PHContentEditingOutput *))completionHandler {
    // Update UI to reflect that editing has finished and output is being rendered.

    // Render and provide output on a background queue.
    dispatch_async(dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0), ^{
        PHContentEditingOutput *output = [[PHContentEditingOutput alloc] initWithContentEditingInput:self.input];

        NSError* error = nil;

        NSData *renderedJPEGData = UIImageJPEGRepresentation(filtered_ui_image, 1.0);
        assert(renderedJPEGData != nil);
        //BOOL written_well = [renderedJPEGData writeToURL:output.renderedContentURL atomically:YES];

        BOOL written_well = [renderedJPEGData writeToURL:output.renderedContentURL options:NSDataWritingAtomic error:&error];
        assert(written_well);



        // Call completion handler to commit edit to Photos.
        completionHandler(output);
    });
}

renderedJPEGData 不是 nil,
error 是 nil，因此函数 [NSData writeToURL] 成功，
written_well 是 YES,

逐行调试时，块完成后，出现警告：

output.renderedContentURL 是 /private/var/mobile/Containers/Data/PluginKitPlugin/509C1A04-D414-4DB7-B1E6-83C47FC88BC9/tmp/blah_blah_name.JPG

所以，我有权限，调试显示没有错误，我可以尝试检测问题的原因是什么？

Answer 1

尽管 header 暗示 adjustmentData 可以为零，但文档指出：

If you write new asset content to the URL specified by the renderedContentURL property, you must also provide a new, distinct PHAdjustmentData object describing your edit. Passing a preexisting adjustment data object (that describes an earlier edit) results in undefined behavior.

所以在调用完成处理程序之前做这样的事情：

output.adjustmentData = [[PHAdjustmentData alloc] initWithFormatIdentifier:@"com.whatever.app" formatVersion:@"1.0" data:[NSData data]];

Answer 2

从iOS10开始，调整数据必须至少有一个字节。这是 iOS 9 的重大变化，其中调整数据可以为零。我已经在 iOS 9 和 iOS 10 上进行了测试以确认。

其他文档：https://developer.apple.com/reference/photos/phcontenteditingoutput/1518684-adjustmentdata

PHContentEditingOutput* output = [[PHContentEditingOutput alloc] initWithContentEditingInput:self.input];
NSMutableData* adjustmentData = [NSMutableData data];
uint8_t byte = 1;
[adjustmentData appendBytes:&byte length:1];
output.adjustmentData = [[PHAdjustmentData alloc] initWithFormatIdentifier:@"com.yourcompany.yourapp" formatVersion:@"1.0f" data:adjustmentData];

iOS 照片扩展 finishContentEditing WithCompletionHandler：无法保存更改

iOS photo extension finishContentEditingWithCompletionHandler: Unable to Save Changes

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