問題描述

我的應用中有一個 UIScrollView，并且我在其他一些應用中看到，當用戶滾動時，頂部會在滾動時淡出，而不僅僅是消失.

我真的很喜歡這個效果并且想要實現它.有什么想法可以做到嗎?

簡單的2020解決方案:

導入 UIKit類 FadeTail: UIIView {私有惰性 var gradientLayer: CAGradientLayer = {讓 l = CAGradientLayer()l.startPoint = CGPoint(x: 0.5, y: 0)l.endPoint = CGPoint(x: 0.5, y: 1)讓 baseColor = UIColor.white//例如l.colors = [baseColor.withAlphaComponent(0),baseColor.withAlphaComponent(1),].map{$0.cgColor}layer.addSublayer(l)返回 l}()覆蓋 func layoutSubviews() {super.layoutSubviews()gradientLayer.frame = 邊界}}

簡單

• 在情節提要中自動布局該視圖，
• 任何您想要的形狀或大小
• 在您希望淡出的視圖(文本、圖像、網絡視圖、任何內容)之上.

簡單.

提示 - 漸變、圓圈等

如果您需要瘋狂的圓形/帶狀/等漸變，請使用此處的技術:

I've got a UIScrollView in my app and I have seen in some other apps that when the user scrolls, the top section fades out on scroll rather than just dissapearing out.

I really love this effect and want to achieve it. Any ideas how it can be done?

Simple 2020 solution:

import UIKit

class FadeTail: UIIView {
    
    private lazy var gradientLayer: CAGradientLayer = {
        let l = CAGradientLayer()
        l.startPoint = CGPoint(x: 0.5, y: 0)
        l.endPoint = CGPoint(x: 0.5, y: 1)
        let baseColor = UIColor.white // for example
        l.colors = [
            baseColor.withAlphaComponent(0),
            baseColor.withAlphaComponent(1),
        ].map{$0.cgColor}
        layer.addSublayer(l)
        return l
    }()
    
    override func layoutSubviews() {
        super.layoutSubviews()
        gradientLayer.frame = bounds
    }
}

Simply

• autolayout that view in storyboard,
• any shape or size you wish
• on top of the view (text, image, webview, anything) you wish to be faded.

Easy.

Tip - gradients, circles, etc

If you need crazy circular/banded/etc fades, use the techniques here: https://stackoverflow.com/a/61174086/294884

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