How to add gradient color to UIView using Custom Class and UIAppearnace() in swift

Question

Hello Everyone I want to add Gradient Background Color to UIView using UIAppearnce() with CustomView Class .I am facing an error - Thread 1: " Illegal axis type, @, for appearance setter, setBorderGradientColortoView1WithFirstColor:secondColor:. Expected NSInteger or NSUInteger" . I attached my code.

import Foundation
import UIKit
import SwiftHEXColors

class CustomUIViewClass: UIView {

@objc dynamic var subviewColor: UIColor? {
        get { return self.backgroundColor }
        set { self.backgroundColor = newValue }
    }

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

required init?(coder: NSCoder) {
    super.init(coder: coder)
    setup()
}


@objc dynamic func setup(){
   self.backgroundColor = .yellow
    self.frame.size.height = 250
    self.layer.borderWidth = 5
    self.backgroundColor = subviewColor
    
}

@objc dynamic func setBorderGradientColortoView1(firstColor : String , secondColor : String)  {
    let colorTop =  UIColor(hexString : firstColor )!.cgColor
    let colorBottom = UIColor(hexString : secondColor)!.cgColor
    let gradientLayer = CAGradientLayer()
    gradientLayer.colors = [colorTop, colorBottom]
    gradientLayer.locations = [0.0, 1.0]
    gradientLayer.frame = self.bounds
   gradientLayer.cornerRadius = self.layer.cornerRadius
    self.layer.sublayers?.filter{ $0 is CAGradientLayer }.forEach{ $0.removeFromSuperlayer() }
 
    self.layer.insertSublayer(gradientLayer, at:0)
}

}

//Setting the value in View Controller CustomUIViewClass.appearance().setBorderGradientColortoView1(firstColor: "#FF2222", secondColor: "#7A1111")

//Error Thread 1: "*** Illegal axis type, @, for appearance setter, setBorderGradientColortoView1WithFirstColor:secondColor:. Expected NSInteger or NSUInteger"

Answer 1

From Apple's docs :

The property type may be any standard iOS type: id , NSInteger , NSUInteger , CGFloat , CGPoint , CGSize , CGRect , UIEdgeInsets or UIOffset . Axis parameter values must be either NSInteger or NSUInteger . UIKit throws an exception if other types are used in the axes.

You're trying to use String

You could change your func to:

@objc dynamic func setBorderGradientColortoView1(firstColor: Int, secondColor: Int)  {
    
    let c1 = UIColor(red: CGFloat((firstColor >> 16) & 0xff) / 255.0, green: CGFloat((firstColor >> 8) & 0xff) / 255.0, blue: CGFloat(firstColor & 0xff) / 255.0, alpha: 1.0)
    let c2 = UIColor(red: CGFloat((secondColor >> 16) & 0xff) / 255.0, green: CGFloat((secondColor >> 8) & 0xff) / 255.0, blue: CGFloat(secondColor & 0xff) / 255.0, alpha: 1.0)

    let colorTop = c1.cgColor
    let colorBottom = c2.cgColor
    
    let gradientLayer = CAGradientLayer()
    gradientLayer.colors = [colorTop, colorBottom]
    gradientLayer.locations = [0.0, 1.0]
    gradientLayer.frame = self.bounds
    gradientLayer.cornerRadius = self.layer.cornerRadius
    self.layer.sublayers?.filter{ $0 is CAGradientLayer }.forEach{ $0.removeFromSuperlayer() }
    
    self.layer.insertSublayer(gradientLayer, at:0)
    
}

and then call it with:

CustomUIViewClass.appearance().setBorderGradientColortoView1(firstColor: 0xff2222, secondColor: 0x7a1111)

If you're getting your values as "#000000" format strings, first convert the string to an Int and pass that value.