Show UIImageView at a size smaller than its intrinsic size - ios

Question

Having adopted Autolayout and Storyboards, I'm no longer designing screens at exact dimensions, so when I use images I tend to use a fairly large sized image so that it will look sharp on the iPad but can be scaled down for the smaller iPhones. I drag this image into the Asset Catalog.
When I place the image into a View Controller in my Storyboard, the image wants to be its intrinsic size. I can only get it to show smaller by setting a specific width, proportional width to another object, or by constraining it between two other items.
I'm now at another point of the project where I need to add the image in code. Although I am setting a specific height and width for the image's frame, the image still appears on screen at its intrinsic size and not where I have set it using:
myImage.frame = CGRect(x: self.view.center.x - 50, y: 100, width: 100, height: 100)
Any ideas on what I'm missing? Thanks!

Answer 1

I look you want add an imageView in CenterX and margin top 100. And hold image aspect in square size 100, 100. This code below will help you.
let imageName = "your image name in resource"
let imageView = UIImageView(frame: CGRectMake(0, 0, 200, 200))
imageView.image = UIImage(named: imageName)
imageView.contentMode = .ScaleAspectFit
imageView.setTranslatesAutoresizingMaskIntoConstraints(false)
self.view.addSubview(imageView)
// add your constraint
let constTop = NSLayoutConstraint(item: imageView, attribute:.Top, relatedBy: .Equal, toItem: self.view, attribute: .Top, multiplier: 1, constant: 100)
// var constLeading = NSLayoutConstraint(item: imageView, attribute: .Leading, relatedBy: .Equal, toItem: self.view, attribute: .Leading, multiplier: 1, constant: self.view.center.x - 50)
var constCenterX = NSLayoutConstraint(item: imageView, attribute: .CenterX, relatedBy: .Equal, toItem: self.view, attribute: .CenterX, multiplier: 1, constant: 0);
var constWidth = NSLayoutConstraint(item: imageView, attribute: .Width, relatedBy: .Equal, toItem: nil, attribute: .Width, multiplier: 1, constant: 100);
var constHight = NSLayoutConstraint(item: imageView, attribute: .Height, relatedBy: .Equal, toItem: nil, attribute: .Height, multiplier: 1, constant: 100);
imageView.addConstraints([constHight, constWidth])
self.view.addConstraints([constTop, constCenterX])
Hope this helps!

Answer 2

You need to set the UIImageView's contentMode which is actually a property of UIView:
https://developer.apple.com/library/prerelease/ios/documentation/UIKit/Reference/UIView_Class/index.html#//apple_ref/swift/enum/c:#E#UIViewContentMode
If you take on layout in code, I hope you're doing it in the right place... by overriding layoutSubviews(), and if that needs to get triggered by an external event, that the event fires setNeedsLayout() on the parent view.
Lots of handshaking and configuring to do if it must be done in code.