ios - 如何将 UIImage 调整为特定大小

Question

在我的应用程序中，我正在用相机拍照并以 320*320 显示UIView。但是由于图像分辨率超过了UIView它的样子，看起来有点挤压。有什么办法可以调整该图像的大小吗？

Answer 1

以下是如何在保留其纵横比的同时调整图像大小。下面的代码来自一个类别UIImage：

+ (UIImage*)imageWithImage:(UIImage *)image 
              scaledToSize:(CGSize)newSize
{

    float heightToWidthRatio = image.size.height / image.size.width;
    float scaleFactor = 1;
    if(heightToWidthRatio > 0) {
        scaleFactor = newSize.height / image.size.height;
    } else {
        scaleFactor = newSize.width / image.size.width;
    }

    CGSize newSize2 = newSize;
    newSize2.width = image.size.width * scaleFactor;
    newSize2.height = image.size.height * scaleFactor;

    UIGraphicsBeginImageContext(newSize2);
    [image drawInRect:CGRectMake(0,0,newSize2.width,newSize2.height)];
    UIImage* newImage = UIGraphicsGetImageFromCurrentImageContext();
    UIGraphicsEndImageContext();

    return newImage;
}

Answer 2

我这样做，但首先我将照片选择器启用为可编辑，因此它是默认的 1:1 纵横比，如下所示：

imgPicker.allowsImageEditing = YES; //I think this is what you're really looking for

然后我使用这种方法调整图像的大小：

-(UIImage*)resizeImage:(UIImage*)image{
    CGSize newSize = CGSizeMake(480.0, 480.0);
    UIGraphicsBeginImageContext(newSize);
        [image drawInRect:CGRectMake(0,0,newSize.width,newSize.height)];
        UIImage* newImage = UIGraphicsGetImageFromCurrentImageContext();
    UIGraphicsEndImageContext();
    return newImage;
}