当其框架与 UIView 相交时反转 UIlabel 文本颜色

Question

您好我试图在标签矩形与 UIView 相交的情况下更改 UILabel 的文本颜色，我在想也许有一个属性或我可以使用的东西。如下图所示：

以前是否有人遇到过这个问题，或者我应该阅读什么来开始做这件事？

提前致谢

Answer 1

好拼图！这是我要做的：

1. 两个 UIView。让我们称一个为背景，另一个为progressBar。 progressBar 堆叠在背景顶部，在它们的共同 superview 上具有相同的 origin。
2. 它们都有一个 UILabel 作为子视图，并且两个标签相对于它们的父级位于同一原点。背景是深色的backgroundColor，它的标签是浅色的textColor，而进度视图则相反。
3. progressBar 的框架宽度比背景窄，并且有clipsToBounds==YES

诀窍是，视图的来源相同，标签的来源相同，顶视图上有 clipsToBounds，一切都会看起来正确。

将这两个视图拖放到一个新的 UIView 子类中，称为 RealCoolProgressView，并为其提供一个公共方法：

-(void)setProgress:(float)progress 进度是一个从 0.0 到 1.0 的数字。该方法缩放progressBar宽度并设置both标签的文本@"Progress %f", progress*100

Answer 2

为任何正在寻找实际应用程序的人用 Swift 构建一个示例。关于这个 danh 的很好的指导 - 谢谢！

---

import UIKit

class CDSlideView: UIView {

    var leftBackView: UIView!
    var leftBackLabel: UILabel!
    var leftFrontView: UIView!
    var leftFrontLabel: UILabel!

    var rightBackView: UIView!
    var rightBackLabel: UILabel!
    var rightFrontView: UIView!
    var rightFrontLabel: UILabel!

    var foregroundView: UIView!
    var backgroundView: UIView!

    var slideGesture: UIPanGestureRecognizer!

    let lightColor: UIColor = UIColor.whiteColor()
    let darkColor: UIColor = UIColor.blueColor()
    let leftText: String = "Search"
    let rightText: String = "New"

    var viewWidth: CGFloat!
    var viewHeight: CGFloat!
    var leftOrigin: CGFloat!
    var rightOrigin: CGFloat!
    var foregroundPadding: CGFloat = 4

    override init(frame: CGRect) {
        super.init(frame: frame)

        // Init variables variables
        viewWidth = self.frame.size.width
        viewHeight = self.frame.size.height
        leftOrigin = foregroundPadding / 2
        rightOrigin = (viewWidth - foregroundPadding) / 2 + foregroundPadding / 2

        backgroundView = UIView()
        backgroundView.frame = CGRectMake(0, 0, viewWidth, viewHeight)
        backgroundView.layer.cornerRadius = backgroundView.frame.size.height / 2
        self.addSubview(backgroundView)

        leftBackView = UIView()
        leftBackView.frame = CGRectMake(0, 0, backgroundView.frame.size.width / 2, backgroundView.frame.size.height)
        self.backgroundView.addSubview(leftBackView)

        leftBackLabel = UILabel()
        leftBackLabel.frame = CGRectMake(0, 0, leftBackView.frame.size.width, leftBackView.frame.size.height)
        leftBackLabel.font = UIFont.systemFontOfSize(13, weight: UIFontWeightSemibold)
        leftBackLabel.backgroundColor = UIColor.clearColor()
        leftBackLabel.lineBreakMode = .ByClipping
        leftBackLabel.textAlignment = .Center
        self.leftBackView.addSubview(leftBackLabel)

        rightBackView = UIView()
        rightBackView.frame = CGRectMake(backgroundView.frame.size.width / 2, 0, backgroundView.frame.size.width / 2, backgroundView.frame.size.height)
        self.backgroundView.addSubview(rightBackView)

        rightBackLabel = UILabel()
        rightBackLabel.frame = CGRectMake(0, 0, rightBackView.frame.size.width, rightBackView.frame.size.height)
        rightBackLabel.font = UIFont.systemFontOfSize(13, weight: UIFontWeightSemibold)
        rightBackLabel.backgroundColor = UIColor.clearColor()
        rightBackLabel.lineBreakMode = .ByClipping
        rightBackLabel.textAlignment = .Center
        self.rightBackView.addSubview(rightBackLabel)

        foregroundView = UIView()
        foregroundView.frame = CGRectMake(foregroundPadding / 2, foregroundPadding / 2, (backgroundView.frame.size.width - foregroundPadding) / 2, backgroundView.frame.size.height - foregroundPadding)
        foregroundView.clipsToBounds = true
        foregroundView.layer.cornerRadius = (foregroundView.frame.size.height - foregroundPadding / 2) / 2
        self.addSubview(foregroundView)

        slideGesture = UIPanGestureRecognizer(target: self, action: #selector(CDSlideView.slideAction))
        self.foregroundView.addGestureRecognizer(slideGesture)

        leftFrontView = UIView()
        leftFrontView.frame = CGRectMake(0, 0, backgroundView.frame.size.width / 2, backgroundView.frame.size.height)
        self.foregroundView.addSubview(leftFrontView)

        leftFrontLabel = UILabel()
        leftFrontLabel.font = UIFont.systemFontOfSize(13, weight: UIFontWeightSemibold)
        leftFrontLabel.backgroundColor = UIColor.clearColor()
        leftFrontLabel.translatesAutoresizingMaskIntoConstraints = false
        leftFrontLabel.lineBreakMode = .ByClipping
        leftFrontLabel.textAlignment = .Center
        self.leftFrontView.addSubview(leftFrontLabel)

        let leftFrontLabelLeadingConstraint = NSLayoutConstraint(item: leftFrontLabel, attribute: .Leading, relatedBy: .Equal, toItem: self, attribute: .Leading, multiplier: 1, constant: self.backgroundView.frame.origin.x)
        self.addConstraint(leftFrontLabelLeadingConstraint)

        let leftFrontLabelTopConstraint = NSLayoutConstraint(item: leftFrontLabel, attribute: .Top, relatedBy: .Equal, toItem: self, attribute: .Top, multiplier: 1, constant: self.backgroundView.frame.origin.y)
        self.addConstraint(leftFrontLabelTopConstraint)

        let leftFrontLabelWidthConstraint = NSLayoutConstraint(item: leftFrontLabel, attribute: .Width, relatedBy: .Equal, toItem: nil, attribute: .NotAnAttribute, multiplier: 1, constant: leftFrontView.frame.size.width)
        self.addConstraint(leftFrontLabelWidthConstraint)

        let leftFrontLabelHeightConstraint = NSLayoutConstraint(item: leftFrontLabel, attribute: .Height, relatedBy: .Equal, toItem: nil, attribute: .NotAnAttribute, multiplier: 1, constant: leftFrontView.frame.size.height)
        self.addConstraint(leftFrontLabelHeightConstraint)

        rightFrontView = UIView()
        rightFrontView.frame = CGRectMake(backgroundView.frame.size.width / 2, 0, backgroundView.frame.size.width / 2, backgroundView.frame.size.height)
        self.foregroundView.addSubview(rightFrontView)

        rightFrontLabel = UILabel()
        rightFrontLabel.font = UIFont.systemFontOfSize(13, weight: UIFontWeightSemibold)
        rightFrontLabel.backgroundColor = UIColor.clearColor()
        rightFrontLabel.translatesAutoresizingMaskIntoConstraints = false
        rightFrontLabel.lineBreakMode = .ByClipping
        rightFrontLabel.textAlignment = .Center
        self.rightFrontView.addSubview(rightFrontLabel)

        let rightFrontLabelTrailingConstraint = NSLayoutConstraint(item: self, attribute: .Trailing, relatedBy: .Equal, toItem: rightFrontLabel, attribute: .Trailing, multiplier: 1, constant: self.backgroundView.frame.origin.x)
        self.addConstraint(rightFrontLabelTrailingConstraint)

        let rightFrontLabelTopConstraint = NSLayoutConstraint(item: rightFrontLabel, attribute: .Top, relatedBy: .Equal, toItem: self, attribute: .Top, multiplier: 1, constant: self.backgroundView.frame.origin.y)
        self.addConstraint(rightFrontLabelTopConstraint)

        let rightFrontLabelWidthConstraint = NSLayoutConstraint(item: rightFrontLabel, attribute: .Width, relatedBy: .Equal, toItem: nil, attribute: .NotAnAttribute, multiplier: 1, constant: rightFrontView.frame.size.width)
        self.addConstraint(rightFrontLabelWidthConstraint)

        let rightFrontLabelHeightConstraint = NSLayoutConstraint(item: rightFrontLabel, attribute: .Height, relatedBy: .Equal, toItem: nil, attribute: .NotAnAttribute, multiplier: 1, constant: rightFrontView.frame.size.height)
        self.addConstraint(rightFrontLabelHeightConstraint)

        let leftTapGesture: UITapGestureRecognizer = UITapGestureRecognizer(target: self, action: #selector(CDSlideView.leftTap(_:)))
        self.leftBackView.addGestureRecognizer(leftTapGesture)

        let rightTapGesture: UITapGestureRecognizer = UITapGestureRecognizer(target: self, action: #selector(CDSlideView.rightTap(_:)))
        self.rightBackView.addGestureRecognizer(rightTapGesture)

        self.setLabelText(leftText, rightText: rightText)
        self.setLightColor(lightColor)
        self.setDarkColor(darkColor)
    }

    required init?(coder aDecoder: NSCoder) {
        fatalError("init(coder:) has not been implemented")
    }

    // MARK: Setup
    func setLightColor(lightColor: UIColor) {
        let lightColor = lightColor
        self.foregroundView.backgroundColor = lightColor
        self.leftBackLabel.textColor = lightColor
        self.rightBackLabel.textColor = lightColor
    }

    func setDarkColor(darkColor: UIColor) {
        let darkColor = darkColor
        self.backgroundView.backgroundColor = darkColor
        self.leftFrontLabel.textColor = darkColor
        self.rightFrontLabel.textColor = darkColor
    }

    func setLabelText(leftText: String, rightText: String) {
        self.leftFrontLabel.text = leftText
        self.leftBackLabel.text = leftText
        self.rightFrontLabel.text = rightText
        self.rightBackLabel.text = rightText
    }

    // MARK: Actions
    func slideAction(sender: UIPanGestureRecognizer) {
        if sender.state == .Began || sender.state == .Changed {
            let translation = sender.translationInView(self)

            // Calculate where the user is trying to drag
            var newCenter: CGPoint = CGPointMake(sender.view!.center.x + translation.x, sender.view!.center.y)

            // Limit bounds & update center
            newCenter.x = max(self.frame.size.width * 0.25 + foregroundPadding / 2, newCenter.x)
            newCenter.x = min(self.frame.size.width * 0.75 - foregroundPadding / 2, newCenter.x)

            // Set new center
            sender.view!.center = newCenter
            sender.setTranslation(CGPointMake(0,0), inView: self)
        } else if sender.state == .Ended {
            let senderVCX = sender.view?.center.x

            // Snap to side
            if senderVCX <= viewWidth / 2 {
                print("called left")
                sender.view?.frame.origin.x = self.leftOrigin
            } else {
                print("called right")
                sender.view?.frame.origin.x = self.rightOrigin
            }
        }
    }

    func leftTap(sender: UITapGestureRecognizer) {
        UIView.animateWithDuration(0.05) {
            self.foregroundView.frame.origin.x = self.leftOrigin
        }
    }

    func rightTap(sender: UITapGestureRecognizer) {
        UIView.animateWithDuration(0.05) {
            self.foregroundView.frame.origin.x = self.rightOrigin
        }
    }
}

Answer 3

我建议你看看这些方法：

您可以通过检查 NSString 的大小来检查您的字符串有多少与视图重叠，使用以下方法：

[yourString sizeWithFont:yourFont constrainedToSize:maximumAllowedSize];

然后您可以使用 NSMutableAttributedString 将标签字符串的一部分设置为一种颜色，而将后一部分设置为另一种颜色。

//Just an example usage 
//It sets the color of characters starting from 3 to the end to blue
[str addAttribute:NSForegroundColorAttributeName value:[UIColor blueColor] range:NSMakeRange(3, str.length)];


//Now you have to set your string as attributed text just like below
//UILabels now support attributed strings by default which is quite handy

[yourLabel setAttributedString:str];

Answer 4

看看this tutorial for creating alpha masks with text。使用这种技术，您可以实现一个标准进度条，该进度条在前景和背景视图中移动，以实现您想要的效果。