压缩图片 减小app内存消耗

//压缩图片  解决图片过多  内存过大

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

    //实现等比例缩放

    float hfactor = image.size.width/KWidth;

    float vfactor = image.size.height/KHeight;

    float factor = fmaxf(hfactor, vfactor);

    

    //画布大小

    CGFloat newWidth = image.size.width/factor;

    CGFloat newHeight = image.size.height/factor;

    CGSize newSize = CGSizeMake(newWidth, newHeight);

    

    UIGraphicsBeginImageContext(newSize);

    [image drawInRect:SetFrame(0, 0, newWidth, newHeight)];

    UIImage *newImage = UIGraphicsGetImageFromCurrentImageContext();

    UIGraphicsEndImageContext();

    

    //图像压缩

    NSData *newImageData = UIImageJPEGRepresentation(newImage, 0.5);

    

    return [UIImage imageWithData:newImageData];

}