iOS swift : How to properly scale down an image?

Question

我正在使用 AlamofireImage 下载并设置我的 UIImage:

backdrop.af_setImageWithURL(downloadURL)

图像比我要显示的要大得多，所以我遇到了锯齿问题。如何正确调整此图像的大小？

结果:

Answer 1

一旦你有了一个有效的UIImage，你就可以调整任何大小的图像:

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，请参阅此 NShipster