Question

我试图以编程方式调整图像大小以适应屏幕的大小，但是当我构建应用时，图像甚至无法显示。我只看到一个空白的屏幕，有谁知道我做错了什么？

这是我的代码（从其他一些线程中了解到调整图像大小）：

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")


}

Answer 1

以下功能调整图像大小。它需要两个参数：图像和所需的大小。

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:: 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))

Answer 2

首先，检查UIImage(named: "Blokker")是否正在返回图像或为零。如果它返回图像，为了在UIImageView中缩放图像，您可以使用以下方法之一：

UIViewContentModeScaleToFill;
UIViewContentModeScaleAspectFit;
UIViewContentModeScaleAspectFill;

ScaleToFill只是缩放图像。

AspectFit和AspectFill缩放图像，保留它的宽高比。

适合将缩放图像，直到全部显示。填充将缩放图像，直到其中一个边等于UIImageView边之一。

https://developer.apple.com/library/ios/documentation/WindowsViews/Conceptual/ViewPG_iPhoneOS/Art/scale_aspect.jpg

以编程方式调整UIImage的大小并不起作用

2 个答案: