ios – 如何在UISegmentedControl中仅显示所选项目的底部边框？

我是iOS开发的新手,在为课程构建应用程序时遇到了一些麻烦.

我创建了一个分段控件,它的init函数(如下所示)在包含分段控件的视图控制器类中调用.我能够从分段控件类中删除分段控件的所有边框和分隔符,如下所示：

import Foundation
import UIKit

class CashSegmentedControl: UISegmentedControl{

func initUI(){
    removeBorders()
}

func removeBorders(){
    self.tintColor = UIColor.clear

}

我希望它在每个段下面都有一条线当选择了段时(类似于instagram)

我搜索了很多,并在StackOverflow上发现了一些帖子,但它们似乎是旧版本的Swift.我真的很感激这方面的任何帮助,如果有更好的解决方案来定制边界(除了我所做的),我想要了解更多！

非常感谢 ：)

解决方法

在单独的swift文件中添加以下代码(命令N – >新文件)：

extension UISegmentedControl{
    func removeBorder(){
        let backgroundImage = UIImage.getColoredRectImageWith(color: UIColor.white.cgColor,andSize: self.bounds.size)
        self.setBackgroundImage(backgroundImage,for: .normal,barMetrics: .default)
        self.setBackgroundImage(backgroundImage,for: .selected,for: .highlighted,barMetrics: .default)

        let deviderImage = UIImage.getColoredRectImageWith(color: UIColor.white.cgColor,andSize: CGSize(width: 1.0,height: self.bounds.size.height))
        self.setDividerImage(deviderImage,forLeftSegmentState: .selected,rightSegmentState: .normal,barMetrics: .default)
        self.setTitleTextAttributes([NSForegroundColorAttributeName: UIColor.gray],for: .normal)
        self.setTitleTextAttributes([NSForegroundColorAttributeName: UIColor(red: 67/255,green: 129/255,blue: 244/255,alpha: 1.0)],for: .selected)
    }

    func addUnderlineForSelectedSegment(){
        removeBorder()
        let underlineWidth: CGFloat = self.bounds.size.width / CGFloat(self.numberOfSegments)
        let underlineHeight: CGFloat = 2.0
        let underlineXPosition = CGFloat(selectedSegmentIndex * Int(underlineWidth))
        let underLineYPosition = self.bounds.size.height - 1.0
        let underlineFrame = CGRect(x: underlineXPosition,y: underLineYPosition,width: underlineWidth,height: underlineHeight)
        let underline = UIView(frame: underlineFrame)
        underline.backgroundColor = UIColor(red: 67/255,alpha: 1.0)
        underline.tag = 1
        self.addSubview(underline)
    }

    func changeUnderlinePosition(){
        guard let underline = self.viewWithTag(1) else {return}
        let underlineFinalXPosition = (self.bounds.width / CGFloat(self.numberOfSegments)) * CGFloat(selectedSegmentIndex)
        UIView.animate(withDuration: 0.1,animations: {
            underline.frame.origin.x = underlineFinalXPosition
        })
    }
}

extension UIImage{

    class func getColoredRectImageWith(color: CGColor,andSize size: CGSize) -> UIImage{
        UIGraphicsBeginImageContextWithOptions(size,false,0.0)
        let graphicsContext = UIGraphicsGetCurrentContext()
        graphicsContext?.setFillColor(color)
        let rectangle = CGRect(x: 0.0,y: 0.0,width: size.width,height: size.height)
        graphicsContext?.fill(rectangle)
        let rectangleImage = UIGraphicsGetImageFromCurrentImageContext()
        UIGraphicsEndImageContext()
        return rectangleImage!
    }
}

然后从viewDidLoad()方法调用segmentedControl.addUnderlineForSelectedSegment()之后,为分段控件创建一个@IBAction方法,如下所示：

@IBAction func segmentedControlDidChange(_ sender: UISegmentedControl){
        segmentedControl.changeUnderlinePosition()
    }

然后从此方法中调用segmentedControl.changeUnderlinePosition().

不要忘记将故事板中的分段控件连接到刚刚创建的@IBAction方法.

非常重要：不要忘记在故事板中使用自动布局来确定分段控件的大小和位置.

这是结果：

随意问你可能有的任何其他问题:)