如何减小 UIImageView 上图像显示的尺寸

Question

我的问题是，在我的应用程序中，我有 UIImageview、button1、button2。 button1 用于访问保存的照片库中的图像，button2 用于将图像存储在数据库中，

但图像尺寸为（800x800），非常大，我想将其存储为（50x50）尺寸

如何单击button2时缩小图像尺寸？

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

这个类别将为您完成这项工作 -

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;
}

请参阅上一个问题使用 iPhone SDK 调整/优化图像尺寸的最简单方法是什么？以供进一步参考