如何在Swift中调整图像大小？ [英] How to Resize image in Swift?

问题描述

我正在为iOS制作应用，使用 Swift 和Parse.com

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

我试图让用户从中选择一张图片一个图像选择器然后将所选图像的大小调整为200x200像素，然后再上传到我的后端。

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复制应用程序教程此代码用于调整图像大小，但它在Objective-C ....

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200x200px版本（然后上传） ？

并且，thumbnailImage函数在做什么？

推荐答案

图像调整大小函数在swift中如下所示。

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 = 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
}

使用上面的函数并使用200 * 200调整图像大小，如下所示

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

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

请参阅我的博文， 在快速客观C中调整图片 ，有关详细信息。

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

swift3已更新

 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!
}

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