UIImageWriteToSavedPhotosAlbum保存到错误的大小和质量 [英] UIImageWriteToSavedPhotosAlbum saves to wrong size and quality

问题描述

我正在尝试拍摄我应用当前视图的屏幕截图并将其保存到相册（然后通过电子邮件发送或彩信）。

I'm trying to take a screen shot of my app's current view and save it to photo album (to then be emailed or MMS'ed).

UIGraphicsBeginImageContext(self.view.bounds.size); 

[self.view.layer renderInContext:UIGraphicsGetCurrentContext()]; 

UIImage *viewImage = UIGraphicsGetImageFromCurrentImageContext();

UIGraphicsEndImageContext();

UIImageWriteToSavedPhotosAlbum(viewImage, self, @selector(savedPhotoImage:didFinishSavingWithError:contextInfo:), nil);

这是有效的，但是当我从中发送电子邮件时，生成的图像会变大（533x800px）并且压缩很大照片库。

This works but the resulting image apears to be larger (533x800px) and heavily compressed when I email it from the photo library.

我先尝试将UIImage写入文件，然后保存到相册，但仍然遇到同样的问题。

I've tried first writing the UIImage to file and then saving to album but still get the same issue.

如果我在iPhone上使用内置的屏幕截图功能，视图会以320x480正确保存到相册，但上述代码似乎会因某种原因保存更大的图像？

If I used the in-built screenshot functionality on the iPhone the view saves correctly to photo album at 320x480 but the above code appears to save a larger image for some reason?

谢谢！

推荐答案

我找到了一个不错的解决方法，这是基本上将 UIImage 重新包装为PNG，然后保存重新包装的版本。代码看起来像这样：

I found a decent workaround, which is to essentially rewrap the UIImage as a PNG, then save the rewrapped version. Code looks something like this:

UIImage* im = [UIImage imageWithCGImage:myCGRef]; // make image from CGRef
NSData* imdata =  UIImagePNGRepresentation ( im ); // get PNG representation
UIImage* im2 = [UIImage imageWithData:imdata]; // wrap UIImage around PNG representation
UIImageWriteToSavedPhotosAlbum(im2, nil, nil, nil); // save to photo album

这篇关于UIImageWriteToSavedPhotosAlbum保存到错误的大小和质量的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！