iOS Swift：如何正确缩小图像？ [英] iOS Swift: How to properly scale down an image?

问题描述

我正在使用AlamofireImage下载并设置我的UIImage：

I'm using AlamofireImage to download and set my UIImage:

backdrop.af_setImageWithURL(downloadURL)

图像比我要显示的图像大得多，所以我遇到了别名问题。如何正确调整此图像的大小？

The image is substantially larger than what I will be displaying and so I have an issue with aliasing. How can I resize this image properly?

结果：

推荐答案

一旦有了有效的 UIImage ：

func resizedImageWith(image: UIImage, targetSize: CGSize) -> UIImage {

    let imageSize = image.size
    let newWidth  = targetSize.width  / image.size.width
    let newHeight = targetSize.height / image.size.height
    var newSize: CGSize

    if(newWidth > newHeight) {
        newSize = CGSizeMake(imageSize.width * newHeight, imageSize.height * newHeight)
    } else {
        newSize = CGSizeMake(imageSize.width * newWidth,  imageSize.height * newWidth)
    }

    let rect = CGRectMake(0, 0, newSize.width, newSize.height)

    UIGraphicsBeginImageContextWithOptions(newSize, false, 0.0)

    image.drawInRect(rect)

    let newImage = UIGraphicsGetImageFromCurrentImageContext()
    UIGraphicsEndImageContext()

    return newImage
}

对于任何其他查询/修改你有，请参考这个 NShipster

For any other queries/modifications you have, refer this NShipster

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