等比例缩放图片

这是通过一个不大于1的缩放系数来实现，写在UIImage的category中。

+(UIImage *)scaleImage:(UIImage *)image toScale:(float)scaleSize;

先看普通的

+(UIImage *)scaleImage:(UIImage *)image toScale:(float)scaleSize{
    UIGraphicsBeginImageContext(CGSizeMake(image.size.width * scaleSize, image.size.height * scaleSize));
    [image drawInRect:CGRectMake(0, 0, image.size.width * scaleSize, image.size.height * scaleSize)];
    UIImage *scaledImage = UIGraphicsGetImageFromCurrentImageContext();
    UIGraphicsEndImageContext();
    
    return scaledImage;
}

但这样会出现失真问题，图片会变得模糊。应用下边的

+(UIImage *)scaleImage:(UIImage *)image toScale:(float)scaleSize{    
    CGSize newSize = CGSizeMake(image.size.width * scaleSize, image.size.height * scaleSize);
    UIGraphicsBeginImageContextWithOptions(newSize, NO, 0.0);
    [image drawInRect:CGRectMake(0, 0, newSize.width, newSize.height)];
    UIImage* scaledImage = UIGraphicsGetImageFromCurrentImageContext();
    UIGraphicsEndImageContext();
    
    return scaledImage;
}