UIImage resizing scale - ios

Question

I have an image like this:
and I'd like to resize this image to a specific width: let's say 200px where the height should also get calculated. (So the image should keep its width-to-height scale)
This was all I get so far:
extension UIImage {
func resize(newSize1: CGSize) -> UIImage {
let size = self.size
let widthRatio = newSize1.width / size.width
let heightRatio = newSize1.height / size.height
var newSize2: CGSize
if(widthRatio > heightRatio) {
newSize2 = CGSize(width: size.width * heightRatio, height: size.height * heightRatio)
} else {
newSize2 = CGSize(width: size.width * widthRatio, height: size.height * widthRatio)
}
let rect = CGRect(x: 0, y: 0, width: newSize2.width, height: newSize2.height)
UIGraphicsBeginImageContextWithOptions(newSize2, false, 1.0)
self.draw(in: rect)
let newImage = UIGraphicsGetImageFromCurrentImageContext()
UIGraphicsEndImageContext()
return newImage2!
}
}
But the function takes a CGSize size parameter (width AND height) but I just want to get a function that takes the width parameter.
How to edit my code to solve my problem?
Any help would be very appreciated :)
Note: The UIImage should get a smaller resolution (less pixels), not the Image View itself!

Answer 1

For Swift 4 And Swift 3 use below UIImage extension for resizing image. It's calculated height according to given width.
extension UIImage {
func resized(toWidth width: CGFloat) -> UIImage? {
let canvasSize = CGSize(width: width, height: CGFloat(ceil(width/size.width * size.height)))
UIGraphicsBeginImageContextWithOptions(canvasSize, false, scale)
defer { UIGraphicsEndImageContext() }
draw(in: CGRect(origin: .zero, size: canvasSize))
return UIGraphicsGetImageFromCurrentImageContext()
}
}

Answer 2

You can calculate the desired height based on your width and aspect ratio of the image. The same can be applied to the height parameters. Here is a sample of the extension of the UIImage.
extension UIImage {
func resize(width: CGFloat) -> UIImage {
let height = (width/self.size.width)*self.size.height
return self.resize(size: CGSize(width: width, height: height))
}
func resize(height: CGFloat) -> UIImage {
let width = (height/self.size.height)*self.size.width
return self.resize(size: CGSize(width: width, height: height))
}
func resize(size: CGSize) -> UIImage {
let widthRatio = size.width/self.size.width
let heightRatio = size.height/self.size.height
var updateSize = size
if(widthRatio > heightRatio) {
updateSize = CGSize(width:self.size.width*heightRatio, height:self.size.height*heightRatio)
} else if heightRatio > widthRatio {
updateSize = CGSize(width:self.size.width*widthRatio, height:self.size.height*widthRatio)
}
UIGraphicsBeginImageContextWithOptions(updateSize, false, UIScreen.main.scale)
self.draw(in: CGRect(origin: .zero, size: updateSize))
let newImage = UIGraphicsGetImageFromCurrentImageContext()
UIGraphicsEndImageContext()
return newImage!
}
}

Answer 3

Based on the solution from #deoKasuhal I developed the following approach to scale an image so that the bigger size (width or height) don't exceeds a defined maximum size, defined by the parameter 'base'.
Example: if the original size is width = 4000 and height = 3000 and the parameter 'base' is set to 200 the returned image has the size 200 x 150 (or vice versa if height is bigger than width):
extension UIImage {
func resize(toBase base: CGFloat) -> UIImage {
guard base > 0 else {
return self
}
let widthRatio = base / max(self.size.width, 1)
let heightRatio = base / max(self.size.height, 1)
var updateSize = CGSize()
if (widthRatio > heightRatio) {
updateSize = CGSize(width:self.size.width * heightRatio, height:self.size.height * heightRatio)
} else {
updateSize = CGSize(width:self.size.width * widthRatio, height:self.size.height * widthRatio)
}
UIGraphicsBeginImageContextWithOptions(updateSize, false, UIScreen.main.scale)
self.draw(in: CGRect(origin: .zero, size: updateSize))
if let newImage = UIGraphicsGetImageFromCurrentImageContext() {
UIGraphicsEndImageContext()
return newImage
} else {
UIGraphicsEndImageContext()
return self
}
}
}