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@luismachado
Created June 23, 2017 13:53
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Custom UIScrollView with fade effect
//
// FadeScrollView.swift
//
// Created by Luís Machado on 23/06/2017.
// Copyright © 2017 Luis Machado. All rights reserved.
//
import UIKit
class FadeScrollView: UIScrollView, UIScrollViewDelegate {
let fadePercentage: Double = 0.2
let gradientLayer = CAGradientLayer()
let transparentColor = UIColor.clear.cgColor
let opaqueColor = UIColor.black.cgColor
var topOpacity: CGColor {
let scrollViewHeight = frame.size.height
let scrollContentSizeHeight = contentSize.height
let scrollOffset = contentOffset.y
let alpha:CGFloat = (scrollViewHeight >= scrollContentSizeHeight || scrollOffset <= 0) ? 1 : 0
let color = UIColor(white: 0, alpha: alpha)
return color.cgColor
}
var bottomOpacity: CGColor {
let scrollViewHeight = frame.size.height
let scrollContentSizeHeight = contentSize.height
let scrollOffset = contentOffset.y
let alpha:CGFloat = (scrollViewHeight >= scrollContentSizeHeight || scrollOffset + scrollViewHeight >= scrollContentSizeHeight) ? 1 : 0
let color = UIColor(white: 0, alpha: alpha)
return color.cgColor
}
override func layoutSubviews() {
super.layoutSubviews()
self.delegate = self
let maskLayer = CALayer()
maskLayer.frame = self.bounds
gradientLayer.frame = CGRect(x: self.bounds.origin.x, y: 0, width: self.bounds.size.width, height: self.bounds.size.height)
gradientLayer.colors = [topOpacity, opaqueColor, opaqueColor, bottomOpacity]
gradientLayer.locations = [0, NSNumber(floatLiteral: fadePercentage), NSNumber(floatLiteral: 1 - fadePercentage), 1]
maskLayer.addSublayer(gradientLayer)
self.layer.mask = maskLayer
}
func scrollViewDidScroll(_ scrollView: UIScrollView) {
gradientLayer.colors = [topOpacity, opaqueColor, opaqueColor, bottomOpacity]
}
}
@Tulleb
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Tulleb commented Dec 27, 2020

Thanks for this 👏

@dwstar79
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@hanab
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hanab commented Aug 31, 2021

how can I make this work for horizontal scroll view to fade only at the right end?

@horchliam
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Two questions: why conform to UIScrollViewDelegate? The scroll view will call layoutSubviews whenever it is scrolled. Second, Why in line 46 did you use self.bounds.origin.x and not 0? Otherwise this is great! Saved me a ton of time!

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