iOS UIImage节省质量损失？

Question

将UIImage保存到照片库时，我似乎失去了质量。任何想法如何解决它？这是重要的代码：

res.render({content: content});

这是imageWithView方法：

-(IBAction)aExportPhoto:(id)sender
{
UIImage *main = [self imageWithView:imageFrame];
UIImage *water = [self imageWithView:waterFrame];
UIImage *lign = [self imageWithView:lignFrame];

CGRect fMain = imageFrame.frame;
CGRect fWater = waterFrame.frame;
CGRect fLign = lignFrame.frame;

CGSize sMain = fMain.size;
CGSize sWater = fWater.size;
CGSize sLign = fLign.size;

UIGraphicsBeginImageContext(sMain);

[main drawInRect:CGRectMake(0, 0, sMain.width, sMain.height)];
[lign drawInRect:CGRectMake(fMain.origin.x, sMain.height - 25, sMain.width - 45, 20) blendMode:kCGBlendModeNormal alpha:1.0f];
[water drawInRect:CGRectMake(sMain.width - 45, sMain.height - 35, 40, 40) blendMode: kCGBlendModeNormal alpha: 1.0f];

UIImage *newImage = UIGraphicsGetImageFromCurrentImageContext();
UIImageWriteToSavedPhotosAlbum(newImage, nil, nil, nil);
UIGraphicsEndImageContext();

}

提前致谢！

Answer 1

您应该UIGraphicsBeginImageContextWithOptions使用aExportPhoto，就像在imageWithView中一样。 UIGraphicsBeginImageContext使用1（非视网膜分辨率）的比例，并且您想要使用0（设备的比例）。