iPhone CATextLayer不显示其文本

Question

我只是想在UIView层中添加一个CATextlayer。但是，根据下面的代码，我只获得了要在UIView中显示的CATextlayer的背景色，而没有显示任何文本。

谁能提供一个如何使用CATextlayer的提示/示例

  - (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;
    }

Answer 1

对于iOS 5及更高版本，可以按如下方式使用CATextLayer：

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];

您可以将此代码添加到您喜欢的任何函数中。特别是在这里，字体的正确分配是必要的，否则无论您设置什么textColor，您的CATextLayer都将呈现为黑色。

Answer 2

将您的代码更改为：

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];

您还应该在视图控制器的-viewDidLoad中执行此操作。这样，您就知道视图已加载且有效，并且现在可以向其中添加层。

Answer 3

斯威夫特

下面的示例显示了一个带有CATextLayer的视图，该视图使用带有彩色文本的自定义字体。

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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)
    }
} 

我更完整的回答是here。