ios - 从 UIImageView 获取调整大小的图像

Question

我需要将图像数据上传到我的 Parse.com 后端，但我发现我的图片太大了，尺寸不明智。 NSHipster 有一篇关于使用此代码调整图像大小的文章:

import ImageIO

if let imageSource = CGImageSourceCreateWithURL(self.URL, nil) {
    let options: CFDictionary = [
        kCGImageSourceThumbnailMaxPixelSize: max(size.width, size.height) / 2.0,
        kCGImageSourceCreateThumbnailFromImageIfAbsent: true
    ]

    let scaledImage = CGImageSourceCreateThumbnailAtIndex(imageSource, 0, options).flatMap { UIImage(CGImage: $0) }
}

不幸的是，这段代码无法在 Swift 1.2 中编译。特别是有2个问题。 CFDictionary 无法初始化，flatMap 方法无法识别。

Answer 1

这里有一些调整图片大小的函数:

import UIKit

func RBSquareImageTo(image: UIImage, size: CGSize) -> UIImage {
    return RBResizeImage(RBSquareImage(image), size)
}

func RBSquareImage(image: UIImage) -> UIImage {
    var originalWidth  = image.size.width
    var originalHeight = image.size.height

    var edge: CGFloat
    if originalWidth > originalHeight {
        edge = originalHeight
    } else {
        edge = originalWidth
    }

    var posX = (originalWidth  - edge) / 2.0
    var posY = (originalHeight - edge) / 2.0

    var cropSquare = CGRectMake(posX, posY, edge, edge)

    var imageRef = CGImageCreateWithImageInRect(image.CGImage, cropSquare);
    return UIImage(CGImage: imageRef, scale: UIScreen.mainScreen().scale, orientation: image.imageOrientation)
}

func RBResizeImage(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
}

来自 HERE .