iOS - UILabel 上的阴影蔓延

Question

我想在我的 UILabel 中增加阴影的传播，但我找不到这样做的属性。我在下面添加了一张照片来说明问题。

顶部标签是我能够在 Photoshop 中创建的所需效果。底部标签说明了我能够在 iOS 中找到的属性。这是我用于底部标签的代码。

let bottomLabel = UILabel(frame: CGRectMake(0, 0, maxWidth, 18))
bottomLabel.backgroundColor = UIColor.clearColor()
bottomLabel.textColor = UIColor.whiteColor()
bottomLabel.font = UIFont.boldSystemFontOfSize(16)
bottomLabel.text = title
bottomLabel.textAlignment = .Center
bottomLabel.numberOfLines = 1
bottomLabel.layer.shadowOffset = CGSize(width: 0, height: 0)
bottomLabel.layer.shadowOpacity = 1
bottomLabel.layer.shadowRadius = 2

我确实找到了使用第二个标签作为阴影的建议，但这并没有给出预期的结果。这是该标签的代码。

let bottomLabelShadow = UILabel(frame: CGRectMake(0, 1, maxWidth, 18)) 
bottomLabelShadow.backgroundColor = UIColor.clearColor()
bottomLabelShadow.textColor = UIColor.blackColor()
bottomLabelShadow.font = UIFont.boldSystemFontOfSize(16)
bottomLabelShadow.text = title
bottomLabelShadow.textAlignment = .Center
bottomLabelShadow.numberOfLines = 1
bottomLabelShadow.layer.shadowOffset = CGSize(width: 0, height: 0)
bottomLabelShadow.layer.shadowOpacity = 1
bottomLabelShadow.layer.shadowRadius = 2

Answer 1

在操场上似乎对我有用。您只需要增加阴影半径以使其显示为您想要的。

这是我使用的确切 Playground 代码

let view = UIView(frame: CGRectMake(0,0,100,20))
view.backgroundColor = UIColor.yellowColor()

let bottomLabel = UILabel(frame: CGRectMake(0, 0, 100, 20))
bottomLabel.backgroundColor = UIColor.clearColor()
bottomLabel.textColor = UIColor.whiteColor()
bottomLabel.font = UIFont.boldSystemFontOfSize(18)
bottomLabel.text = "Testing"
bottomLabel.textAlignment = .Center
bottomLabel.numberOfLines = 1
bottomLabel.layer.shadowOffset = CGSize(width: 0, height: 0)
bottomLabel.layer.shadowOpacity = 1
bottomLabel.layer.shadowRadius = 6

view.addSubview(bottomLabel)

或者，如果您在模糊视图背景上使用它，您可以使用活力来获得更好的外观效果。

Answer 2

Rikola 作为 Swift 3 的回答：

import UIKit

let view = UIView(frame: CGRect.init(x: 0, y: 0, width: 100, height: 20))
view.backgroundColor = UIColor.yellow

let bottomLabel = UILabel(frame: CGRect.init(x: 0, y: 0, width: 100, height: 20))
bottomLabel.backgroundColor = UIColor.clear
bottomLabel.textColor = UIColor.white
bottomLabel.font = UIFont.boldSystemFont(ofSize: 18)
bottomLabel.text = "Testing"
bottomLabel.textAlignment = .center
bottomLabel.numberOfLines = 1
bottomLabel.layer.shadowOffset = CGSize(width: 0, height: 0)
bottomLabel.layer.shadowOpacity = 1
bottomLabel.layer.shadowRadius = 6

view.addSubview(bottomLabel)

将鼠标悬停在右侧栏中的 view.addSubview(bottomLabel) 打印上时按下小“眼睛”，可以直观地显示标签。

Answer 3

//Try This! Hope this helps!!

// Create a string
let myString = "Shadow"

// Create a shadow
let myShadow = NSShadow()
myShadow.shadowBlurRadius = 3
myShadow.shadowOffset = CGSize(width: 3, height: 3)
myShadow.shadowColor = UIColor.gray

// Create an attribute from the shadow
let myAttribute = [ NSShadowAttributeName: myShadow ]

// Add the attribute to the string
let myAttrString = NSAttributedString(string: myString, attributes: myAttribute)

// set the attributed text on a label
myLabel.attributedText = myAttrString

作为扩展：

extension UILabel {

    func setTextWithShadow(_ string: String) {

        let shadow = NSShadow()
        shadow.shadowBlurRadius = 3
        shadow.shadowOffset = CGSize(width: 3, height: 3)
        shadow.shadowColor = UIColor.black.withAlphaComponent(0.5)

        let attributes = [ NSAttributedString.Key.shadow: shadow ]
        let attributedString = NSAttributedString(string: string, attributes: attributes)

        self.attributedText = attributedString
    }

}