How to Resize image in Swift?

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

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}

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 updated

 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!}

For Swift 4.0 and iOS 10

    extension UIImage {        func resizeImage(_ dimension: CGFloat, opaque: Bool, contentMode: UIViewContentMode = .scaleAspectFit) -> UIImage {            var width: CGFloat            var height: CGFloat            var newImage: UIImage            let size = self.size            let aspectRatio =  size.width/size.height            switch contentMode {                case .scaleAspectFit:                    if aspectRatio > 1 {                            // Landscape image                        width = dimension                        height = dimension / aspectRatio                    } else {                                        // Portrait image                        height = dimension                        width = dimension * aspectRatio                    }            default:                fatalError("UIIMage.resizeToFit(): FATAL: Unimplemented ContentMode")            }            if #available(iOS 10.0, *) {                let renderFormat = UIGraphicsImageRendererFormat.default()                renderFormat.opaque = opaque                let renderer = UIGraphicsImageRenderer(size: CGSize(width: width, height: height), format: renderFormat)                newImage = renderer.image {                    (context) in                    self.draw(in: CGRect(x: 0, y: 0, width: width, height: height))                }            } else {                UIGraphicsBeginImageContextWithOptions(CGSize(width: width, height: height), opaque, 0)                    self.draw(in: CGRect(x: 0, y: 0, width: width, height: height))                    newImage = UIGraphicsGetImageFromCurrentImageContext()!                UIGraphicsEndImageContext()            }            return newImage        }    }

Since @KiritModi 's answer is from 2015, this is the Swift 3.0's version:

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!}