调整 UIImage 大小的最简单方法? [英] The simplest way to resize an UIImage?

问题描述

在我的 iPhone 应用程序中，我用相机拍了一张照片，然后我想将其大小调整为 290*390 像素.我正在使用这种方法来调整图像大小:

In my iPhone app, I take a picture with the camera, then I want to resize it to 290*390 pixels. I was using this method to resize the image :

UIImage *newImage = [image _imageScaledToSize:CGSizeMake(290, 390)
                         interpolationQuality:1];    

它运行良好，但它是一个未记录的功能，所以我不能再在 iPhone OS4 上使用它.

It works perfectly, but it's an undocumented function, so I can't use it anymore with iPhone OS4.

那么……调整 UIImage 大小的最简单方法是什么?

So... what is the simplest way to resize an UIImage ?

推荐答案

最简单的方法是设置你的 UIImageView 的 frame 并将 contentMode 设置为调整大小选项.

The simplest way is to set the frame of your UIImageView and set the contentMode to one of the resizing options.

或者您可以使用此实用方法，如果您确实需要调整图像大小:

Or you can use this utility method, if you actually need to resize an image:

+ (UIImage *)imageWithImage:(UIImage *)image scaledToSize:(CGSize)newSize {
    //UIGraphicsBeginImageContext(newSize);
    // In next line, pass 0.0 to use the current device's pixel scaling factor (and thus account for Retina resolution).
    // Pass 1.0 to force exact pixel size.
    UIGraphicsBeginImageContextWithOptions(newSize, NO, 0.0);
    [image drawInRect:CGRectMake(0, 0, newSize.width, newSize.height)];
    UIImage *newImage = UIGraphicsGetImageFromCurrentImageContext();    
    UIGraphicsEndImageContext();
    return newImage;
}

示例用法:

#import "MYUtil.h"
…
UIImage *myIcon = [MYUtil imageWithImage:myUIImageInstance scaledToSize:CGSizeMake(20, 20)];

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