以编程方式调整 UIImage 的大小不起作用 [英] resize UIImage programmatically doesn't work

问题描述

我试图以编程方式调整我的图像大小以适应屏幕的大小，但是当我构建我的应用程序时，图像甚至不会显示.我只看到一个空白屏幕，有人知道我做错了什么吗?

I was trying to resize my image programmatically to adapt to the screen's size, but when I build my app, the image won't even show. I just see a blank screen, does anyone know what I did wrong?

这是我的代码(从其他一些关于调整图像大小的线程中了解到):

This is my code (learned that from some other threads about resizing images):

class ViewControllerSport: UIViewController {

@IBOutlet weak var FotoSport: UIImageView!

let screen = UIScreen.mainScreen().bounds



override func viewDidLoad() {
    super.viewDidLoad()

    FotoSport.frame = CGRect(x: 20, y: 20, width: screen.width * 0.5, height: screen.width * 0.5)
    FotoSport.image = UIImage(named: "Blokker")


}

推荐答案

以下函数调整图像大小.它需要两个参数:图像和所需的大小.

The following function resizes an image. It takes two arguments: the image and the desired size.

func ResizeImage(image: UIImage, targetSize: CGSize) -> UIImage {
    let size = image.size

    let widthRatio  = targetSize.width  / image.size.width
    let heightRatio = targetSize.height / image.size.height

    // Figure out what our orientation is, and use that to form the rectangle
    var newSize: CGSize
    if(widthRatio > heightRatio) {
        newSize = CGSizeMake(size.width * heightRatio, size.height * heightRatio)
    } else {
        newSize = CGSizeMake(size.width * widthRatio,  size.height * widthRatio)
    }

    // This is the rect that we've calculated out and this is what is actually used below
    let rect = CGRectMake(0, 0, newSize.width, newSize.height)

    // Actually do the resizing to the rect using the ImageContext stuff
    UIGraphicsBeginImageContextWithOptions(newSize, false, 1.0)
    image.drawInRect(rect)
    let newImage = UIGraphicsGetImageFromCurrentImageContext()
    UIGraphicsEndImageContext()

    return newImage
}

用法:

self.ResizeImage(UIImage(named: "MyImage.png")!, targetSize: CGSizeMake(320.0, 700.0))

参考链接:: 调整图片大小

Reference link :: Resize image

Swift 3.0:

func ResizeImage(_ image: UIImage, targetSize: CGSize) -> UIImage? {
    let size = image.size

    let widthRatio  = targetSize.width  / image.size.width
    let heightRatio = targetSize.height / image.size.height

    // Figure out what our orientation is, and use that to form the rectangle
    var newSize: CGSize
    if(widthRatio > heightRatio) {
        newSize = CGSize(width: size.width * heightRatio, height: size.height * heightRatio)
    } else {
        newSize = CGSize(width: size.width * widthRatio, height: size.height * widthRatio)
    }

    // This is the rect that we've calculated out and this is what is actually used below
    let rect = CGRect(x: 0, y: 0, width: newSize.width, height: newSize.height)

    // Actually do the resizing to the rect using the ImageContext stuff
    UIGraphicsBeginImageContextWithOptions(newSize, false, 1.0)
    image.draw(in: rect)
    let newImage = UIGraphicsGetImageFromCurrentImageContext()
    UIGraphicsEndImageContext()

    return newImage
}

用法:

self.ResizeImage(UIImage(named: "MyImage.png")!, targetSize: CGSize(width: 320.0, height: 700.0))

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