Autolayout Programmatically

gistfile1.txt

Normally we use autolayout in Storyboard in iOS.
It's cool and easy to use , what you see is what you get.

Somehow some project's nerd don't think so , they build a project using programmaticlly autolayout.

So here i am , i have to do the home work to find out exactly how to build using Visual Format syntax.

This is a demo , just copy to a new created project :

       let testView = UIView()
        testView.backgroundColor=UIColor.redColor()
        self.view.addSubview(testView)
        testView.setTranslatesAutoresizingMaskIntoConstraints(false)
        testView.addConstraints(NSLayoutConstraint.constraintsWithVisualFormat("H:[testView(width)]", options:nil, metrics: ["width":50], views: ["testView":testView]))
        testView.addConstraints(NSLayoutConstraint.constraintsWithVisualFormat("V:[testView(height)]", options: nil, metrics: ["height":100], views: ["testView":testView]))
        
        
        self.view.addConstraint(NSLayoutConstraint(item: testView, attribute: NSLayoutAttribute.CenterX, relatedBy: NSLayoutRelation.Equal, toItem:self.view, attribute: NSLayoutAttribute.CenterX, multiplier: 1.0, constant: 0.0))
        self.view.addConstraint(NSLayoutConstraint(item: testView, attribute: NSLayoutAttribute.CenterY, relatedBy: NSLayoutRelation.Equal, toItem: self.view, attribute: NSLayoutAttribute.CenterY, multiplier: 1.0, constant: 0.0))