夫特

Question

我只是想在CATextlayer图层中添加UIView。但是，根据以下代码，我只会在CATextlayer中显示UIView的背景颜色，而不显示任何文字。只是想知道我错过了显示文字的内容。

有人可以提供提示/示例如何使用CATextlayer吗？

  - (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，可以使用CATextLayer，如下所示：

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];

您可以在任何您喜欢的功能中添加此代码。特别是在这里正确分配 font 是必要的，否则无论你设置什么textColor，你的CATextLayer都会呈现为黑色。

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。这样您就知道您的视图已加载且有效，现在可以添加图层。

Answer 3

夫特

以下示例显示了使用带有彩色文本的自定义字体的CATextLayer视图。

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)
    }
}

我更全面的回答是here。

Answer 4

您可以自定义CLTextLayer，

    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_];

唐，忘了在视图类中导入CoreText / CoreText.h。感谢...

Answer 5

您应该（反直觉地）在初始化完成后或在您希望它绘制文本时调用textLayer.display()或textLayer.displayIfNeeded()。

Answer 6

根据文档，CATextLayer的默认文本颜色为白色。白色的白色很难看到。

Answer 7

试试这个：

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

iPhone CATextLayer不显示其文本

7 个答案:

夫特