如何在 Swift 中调整图像大小?

问题描述

我正在为 iOS 开发一个应用程序，使用 Swift 和 Parse.com

I am making an app for iOS, using Swift and Parse.com

我试图让用户从图像选择器中选择一张图片，然后在上传到我的后端之前将所选图像的大小调整为 200x200 像素.

I am trying to let the user select a picture from an image picker and then resize the selected image to 200x200 pixels before uploading to my backend.

Parse.com 有一个名为AnyPic"的 Instagram 复制应用程序的教程，它提供了用于调整图像大小的代码，但它是在 Objective-C 中....

Parse.com have a tutorial for an Instagram copy app called "AnyPic" which gives this code for resizing images, but it is in Objective-C....

// Resize the image to be square (what is shown in the preview)
UIImage *resizedImage = [anImage resizedImageWithContentMode:UIViewContentModeScaleAspectFit
        bounds:CGSizeMake(560.0f, 560.0f)
        interpolationQuality:kCGInterpolationHigh];
// Create a thumbnail and add a corner radius for use in table views
UIImage *thumbnailImage = [anImage thumbnailImage:86.0f
        transparentBorder:0.0f
        cornerRadius:10.0f
        interpolationQuality:kCGInterpolationDefault];

如何在 Swift 中创建所选图片的 200x200 像素版本(然后上传)?

还有，thumbnailImage 函数是做什么的?

推荐答案

查看我的博文 在 swift 和objective C 中调整图像大小，了解更多详情.

See my blog post, Resize image in swift and objective C, for further details.

快速调整图像大小功能如下.

Image resize function in swift as below.

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

    let widthRatio  = targetSize.width  / size.width
    let heightRatio = targetSize.height / 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(origin: .zero, size: newSize)

    // 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
}

使用上面的函数，将图片调整为 200*200 如下代码

Use the above function and resize image with 200*200 as below code

self.resizeImage(UIImage(named: "yourImageName")!, targetSize: CGSizeMake(200.0, 200.0))

swift3 更新

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

    let widthRatio  = targetSize.width  / size.width
    let heightRatio = targetSize.height / 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!
}

这篇关于如何在 Swift 中调整图像大小?的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持！