IOS中图片的一些处理方法

1. 图片缩放到指定大小, 但这个会造成图片的清晰度下降

- (UIImage *)imageWithSize:(CGSize)targetSize {
    UIImage *sourceImage = self;
    UIImage *newImage = nil;
    CGFloat targetWidth = targetSize.width;
    CGFloat targetHeight = targetSize.height;
    CGFloat scaledWidth = targetWidth;
    CGFloat scaledHeight = targetHeight;
    CGPoint thumbnailPoint = CGPointMake(0.0,0.0);
    UIGraphicsBeginImageContext(targetSize);
    CGRect thumbnailRect = CGRectZero;
    thumbnailRect.origin = thumbnailPoint;
    thumbnailRect.size.width  = scaledWidth;
    thumbnailRect.size.height = scaledHeight;
    [sourceImage drawInRect:thumbnailRect];
    newImage = UIGraphicsGetImageFromCurrentImageContext();
    UIGraphicsEndImageContext();
    return newImage;
}

 

左图是缩放后的，右图是原图

左边比较模糊。不建议使用这种图片缩放方法，即便是1：1的变化也会造成图片模糊。