Tutorial :iPhone CATextLayer doesn't show its text



Question:

I was simply trying to add a CATextlayer in an UIView layer. However, according to the following code, I only get the CATextlayer's background color to be displayed in the UIView, without any text. Just wonder what I missed to display the text.

Could anyone offer a hint/sample how to use CATextlayer?

  - (id)initWithNibName:(NSString *)nibNameOrNil bundle:(NSBundle *)nibBundleOrNil {          if ((self = [super initWithNibName:nibNameOrNil bundle:nibBundleOrNil])) {              // Custom initialization                CATextLayer *TextLayer = [CATextLayer layer];              TextLayer.bounds = CGRectMake(0.0f, 0.0f, 100.0f, 100.0f);              TextLayer.string = @"Test";              TextLayer.font = [UIFont boldSystemFontOfSize:18].fontName;              TextLayer.backgroundColor = [UIColor blackColor].CGColor;              TextLayer.wrapped = NO;                //TextLayer.backgroundColor = [UIColor blueColor];              self.view = [[UIView alloc] initWithFrame:CGRectMake(0.0f, 0.0f, 100.0f, 100.0f)];              self.view.backgroundColor = [UIColor blueColor];              [self.view.layer addSublayer:TextLayer];              [self.view.layer layoutSublayers];            }          return self;      }  


Solution:1

For iOS 5 and beyond, one can use CATextLayer as follows:

CATextLayer *textLayer = [CATextLayer layer];  textLayer.frame = CGRectMake(144, 42, 76, 21);  textLayer.font = CFBridgingRetain([UIFont boldSystemFontOfSize:18].fontName);  textLayer.fontSize = 18;  textLayer.foregroundColor = [UIColor redColor].CGColor;  textLayer.backgroundColor = [UIColor yellowColor].CGColor;  textLayer.alignmentMode = kCAAlignmentCenter;  textLayer.string = @"BAC";  [self.view.layer addSublayer:textLayer];  

You can add this code in any function you like. Specially here correct assignment of font is necessary, otherwise your CATextLayer will be rendered as black no matter what textColor you set.


Solution:2

Change your code to this:

CATextLayer *TextLayer = [CATextLayer layer];  TextLayer.bounds = CGRectMake(0.0f, 0.0f, 100.0f, 100.0f);  TextLayer.string = @"Test";  TextLayer.font = [UIFont boldSystemFontOfSize:18].fontName;  TextLayer.backgroundColor = [UIColor blackColor].CGColor;  TextLayer.position = CGPointMake(80.0, 80.0f);  TextLayer.wrapped = NO;  [self.view.layer addSublayer:TextLayer];  

You should also be doing this in the view controller's -viewDidLoad. That way you know your view is loaded and valid and can now have layers added to it.


Solution:3

Swift

Here is an example that shows a view with a CATextLayer using a custom font with colored text.

enter image description here

import UIKit  class ViewController: UIViewController {        @IBOutlet weak var myView: UIView!        override func viewDidLoad() {          super.viewDidLoad()            // Attributed string          let myAttributes = [              NSFontAttributeName: UIFont(name: "Chalkduster", size: 30.0)! , // font              NSForegroundColorAttributeName: UIColor.cyanColor()             // text color          ]          let myAttributedString = NSAttributedString(string: "My text", attributes: myAttributes )            // Text layer          let myTextLayer = CATextLayer()          myTextLayer.string = myAttributedString          myTextLayer.backgroundColor = UIColor.blueColor().CGColor          myTextLayer.frame = myView.bounds          myView.layer.addSublayer(myTextLayer)      }  }   

My fuller answer is here.


Solution:4

You can customize the CLTextLayer Like this,

    CATextLayer *aTextLayer_= [[CATextLayer alloc] init];    aTextLayer_.frame =CGRectMake(23.0, 160.0, 243.0, 99.0);    aTextLayer_.font=CTFontCreateWithName( (CFStringRef)@"Courier", 0.0, NULL);        aTextLayer_.string = @"You string put here";    aTextLayer_.wrapped = YES;    aTextLayer_.foregroundColor = [[UIColor greenColor] CGColor];    aTextLayer_.fontSize = 15.f;       aTextLayer_.backgroundColor = [UIColor blackColor].CGColor;    aTextLayer_.alignmentMode = kCAAlignmentCenter;    [self.view.layer addSublayer:aTextLayer_];  

Don,t forgot to import CoreText/CoreText.h in your view-class. Thanks...


Solution:5

You should (counter-intuitively) call textLayer.display() or textLayer.displayIfNeeded() after the initialization is complete or whenever you want it to draw text.


Solution:6

According to the docs, the default text color of a CATextLayer is white. White on white is hard to see.


Solution:7

try this one:

self.view = [[UIView alloc] initWithFrame:CGRectMake(0.0f, 0.0f, 100.0f, 100.0f)];  [self.view setWantsLayer:YES];  self.view.backgroundColor = [UIColor blueColor];  

Note:If u also have question or solution just comment us below or mail us on toontricks1994@gmail.com
Previous
Next Post »