Question

我尝试使用UIImageJPEGRepresentation（img，0）减小图像大小，但内存仍然很高。是否有任何选项可以在不降低图像质量的情况下压缩图像。

Answer 1

CGFloat c = 0.9f;
int maxFileSize = 250*250; //or what ever dimensions u want
NSData *imageData = UIImageJPEGRepresentation(yourImage, c);

while ([imageData length] > maxFileSize && c > 0.1f)
{
    c -= 0.1;
    imageData = UIImageJPEGRepresentation(yourImage, c);
}

Answer 2

用于压缩图像用户此类别

@interface UIImage (ImageCompression)
+(UIImage *)compressImage:(UIImage *)image;
@end

@implementation UIImage (ImageCompression)

+(UIImage *)compressImage:(UIImage *)image{

    float actualHeight = image.size.height;
    float actualWidth = image.size.width;
    float maxHeight = 600.0;
    float maxWidth = 800.0;
    float imgRatio = actualWidth/actualHeight;
    float maxRatio = maxWidth/maxHeight;
    float compressionQuality = 0.5;//50 percent compression

    if (actualHeight > maxHeight || actualWidth > maxWidth){
        if(imgRatio < maxRatio){
            //adjust width according to maxHeight
            imgRatio = maxHeight / actualHeight;
            actualWidth = imgRatio * actualWidth;
            actualHeight = maxHeight;
        }
        else if(imgRatio > maxRatio){
            //adjust height according to maxWidth
            imgRatio = maxWidth / actualWidth;
            actualHeight = imgRatio * actualHeight;
            actualWidth = maxWidth;
        }
        else{
            actualHeight = maxHeight;
            actualWidth = maxWidth;
        }
    }

    CGRect rect = CGRectMake(0.0, 0.0, actualWidth, actualHeight);
    UIGraphicsBeginImageContext(rect.size);
    [image drawInRect:rect];
    UIImage *img = UIGraphicsGetImageFromCurrentImageContext();
    NSData *imageData = UIImageJPEGRepresentation(img, compressionQuality);
    UIGraphicsEndImageContext();

    return [UIImage imageWithData:imageData];

}

@end

减少ios中的图像大小

2 个答案: