NSString draw(in: rect) method changes rect by itself

Question

I am trying to draw a string in a UIView.

class ViewController: UIViewController {

override func viewDidLoad() {
    super.viewDidLoad()
    // Do any additional setup after loading the view, typically from a nib.

    let anotheR: anotherView = anotherView(frame: view.bounds)
    view.backgroundColor = UIColor.yellow
    view.addSubview(anotheR)
    anotheR.backgroundColor = UIColor.lightGray
    anotheR.draw(CGRect(x: 100, y: 300, width: 50, height: 10))

}


override func didReceiveMemoryWarning() {
    super.didReceiveMemoryWarning()
    // Dispose of any resources that can be recreated.
}


}

class anotherView: UIView {

override func draw(_ rect: CGRect) {
    let suprect = rect
 var string = "Lorem Ipsum is simply dummy text of the printing and typesetting industry. Lorem Ipsum has been the industry's standard dummy text ever since the 1500s." as NSString
    string.draw(in: rect, withAttributes:  [NSForegroundColorAttributeName: UIColor.red, NSFontAttributeName: UIFont.systemFont(ofSize: 24)])

}
}

So there is a view and I overrode UIViews function draw(in:) to write a string in a view. So it writes a string but not it specified rectangle (CGRect(x: 100, y: 300, width: 50, height: 10)) . It just draw it in CGrect(x:0,y:0,width: frame.width, height: frame.height). So it changes rect by itself during runtime.

Here it is: 1) programm begins to call anotheR.draw(CGRect(x: 100, y: 300, width: 50, height: 10)) method.

2) CGRect somehow changes to CGRect(x:0,y:0,width: frame.width, height: frame.height) Please maybe someone knows whats happen? It exposed all code I had wrote. Thank you!

Please learn how drawing works (Paragraph The Drawing Cycle). You must not call drawRect by yourself. It's called by the framework when the view is marked to be redrawn. — vadian

Razib Mollick Razib Mollick · Accepted Answer · 2018-04-04T20:38:21

The solution from SK_khan is correct. In case if you like to keep your anotherView bound same with controller view bound, you can choose to set the CGRect hard value inside your draw method like this.

string.draw(in: CGRect(x: 100, y: 300, width: 50, height: 10), withAttributes:  [NSAttributedStringKey.foregroundColor: UIColor.red, NSAttributedStringKey.font: UIFont.systemFont(ofSize: 24)])

NSString draw(in: rect) method changes rect by itself

2 Answers