如何缩小UIImageView上的图像显示尺寸

Question

我的问题是，在我的应用程序中有UIImageview，button1，button2。用button2将图像存入数据库，用button1从保存的图片库中存取图像，

但是图像大小是(800x800)，这是非常大的，我想以(50x50)大小存储它

如何在点击button2时缩小图片大小？

Answer 1

// grab the original image
UIImage *originalImage = [UIImage imageNamed:@"myImage.png"];

UIImage *scaledImage = [UIImage imageWithCGImage:[originalImage CGImage] scale:50/800 orientation:UIImageOrientationUp];

Answer 2

这个类别将为您做这项工作-

UIImage+Additions.h -

@interface UIImage (UIImageAdditions)
- (UIImage*)scaleToSize:(CGSize)size;
@end

UIImage+Additions.m -

@implementation UIImage (UIImageAdditions)

- (UIImage*)scaleToSize:(CGSize)size {
    UIGraphicsBeginImageContext(size);

    CGContextRef context = UIGraphicsGetCurrentContext();
    CGContextTranslateCTM(context, 0.0, size.height);
    CGContextScaleCTM(context, 1.0, -1.0);

    CGContextDrawImage(context, CGRectMake(0.0f, 0.0f, size.width, size.height), self.CGImage);

    UIImage* scaledImage = UIGraphicsGetImageFromCurrentImageContext();

    UIGraphicsEndImageContext();

    return scaledImage;
}
@end

Answer 3

+ (UIImage*)imageWithImage:(UIImage*)image 
               scaledToSize:(CGSize)newSize;
{
   UIGraphicsBeginImageContext( newSize );
   [image drawInRect:CGRectMake(0,0,newSize.width,newSize.height)];
   UIImage* newImage = UIGraphicsGetImageFromCurrentImageContext();
   UIGraphicsEndImageContext();

   return newImage;
}

请参阅前面的SO问题What's the easiest way to resize/optimize an image size with the iPhone SDK?以获得进一步的参考