How can I set the UINavigationbar with gradient color?
I want to set the UINavigationbar backgroundColor to a gradient color where I would like to set it via an array of colors to create a Gradient, ideally, as accessible methods inside UINavigationBar to change its color to this gradient.
Any suggestions? (Aside from setting an image manually as the background image of the navigation bar)
Details
- Xcode 11.4 (11E146), swift 5
- Tested on iOS 13.1, 12.2, 11.0.1
Solution
class UINavigationBarGradientView: UIView {
enum Point {
case topRight, topLeft
case bottomRight, bottomLeft
case custom(point: CGPoint)
var point: CGPoint {
switch self {
case .topRight: return CGPoint(x: 1, y: 0)
case .topLeft: return CGPoint(x: 0, y: 0)
case .bottomRight: return CGPoint(x: 1, y: 1)
case .bottomLeft: return CGPoint(x: 0, y: 1)
case .custom(let point): return point
}
}
}
private weak var gradientLayer: CAGradientLayer!
convenience init(colors: [UIColor], startPoint: Point = .topLeft,
endPoint: Point = .bottomLeft, locations: [NSNumber] = [0, 1]) {
self.init(frame: .zero)
let gradientLayer = CAGradientLayer()
gradientLayer.frame = frame
layer.addSublayer(gradientLayer)
self.gradientLayer = gradientLayer
set(colors: colors, startPoint: startPoint, endPoint: endPoint, locations: locations)
backgroundColor = .clear
}
func set(colors: [UIColor], startPoint: Point = .topLeft,
endPoint: Point = .bottomLeft, locations: [NSNumber] = [0, 1]) {
gradientLayer.colors = colors.map { $0.cgColor }
gradientLayer.startPoint = startPoint.point
gradientLayer.endPoint = endPoint.point
gradientLayer.locations = locations
}
func setupConstraints() {
guard let parentView = superview else { return }
translatesAutoresizingMaskIntoConstraints = false
topAnchor.constraint(equalTo: parentView.topAnchor).isActive = true
leftAnchor.constraint(equalTo: parentView.leftAnchor).isActive = true
parentView.bottomAnchor.constraint(equalTo: bottomAnchor).isActive = true
parentView.rightAnchor.constraint(equalTo: rightAnchor).isActive = true
}
override func layoutSubviews() {
super.layoutSubviews()
guard let gradientLayer = gradientLayer else { return }
gradientLayer.frame = frame
superview?.addSubview(self)
}
}
extension UINavigationBar {
func setGradientBackground(colors: [UIColor],
startPoint: UINavigationBarGradientView.Point = .topLeft,
endPoint: UINavigationBarGradientView.Point = .bottomLeft,
locations: [NSNumber] = [0, 1]) {
guard let backgroundView = value(forKey: "backgroundView") as? UIView else { return }
guard let gradientView = backgroundView.subviews.first(where: { $0 is UINavigationBarGradientView }) as? UINavigationBarGradientView else {
let gradientView = UINavigationBarGradientView(colors: colors, startPoint: startPoint,
endPoint: endPoint, locations: locations)
backgroundView.addSubview(gradientView)
gradientView.setupConstraints()
return
}
gradientView.set(colors: colors, startPoint: startPoint, endPoint: endPoint, locations: locations)
}
}
Usage
navigationBar.setGradientBackground(colors: [.lightGray, .red], startPoint: .topLeft, endPoint: .bottomRight)
Create gradient layer and add it as background of navigation bar.
CAGradientLayer *gradient = [CAGradientLayer layer];
gradient.frame = self.navigationController.navigationBar.bounds;
gradient.colors = [NSArray arrayWithObjects:(id)[[UIColor whiteColor] CGColor], (id)[[UIColor blackColor] CGColor], nil];
[self.navigationController.navigationBar setBackgroundImage:[self imageFromLayer:gradient] forBarMetrics:UIBarMetricsDefault];
For creating image from layer.
- (UIImage *)imageFromLayer:(CALayer *)layer
{
UIGraphicsBeginImageContext([layer frame].size);
[layer renderInContext:UIGraphicsGetCurrentContext()];
UIImage *outputImage = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
return outputImage;
}
One more thing, there is one library available in github : CRGradientNavigationBar you can also use this library.
In Swift 3, Swift 4 and Swift 5:
let gradient = CAGradientLayer()
let sizeLength = UIScreen.main.bounds.size.height * 2
let defaultNavigationBarFrame = CGRect(x: 0, y: 0, width: sizeLength, height: 64)
gradient.frame = defaultNavigationBarFrame
gradient.colors = [UIColor.white.cgColor, UIColor.black.cgColor]
UINavigationBar.appearance().setBackgroundImage(self.image(fromLayer: gradient), for: .default)
For creating image from layer:
func image(fromLayer layer: CALayer) -> UIImage {
UIGraphicsBeginImageContext(layer.frame.size)
layer.render(in: UIGraphicsGetCurrentContext()!)
let outputImage = UIGraphicsGetImageFromCurrentImageContext()
UIGraphicsEndImageContext()
return outputImage!
}
In Swift 2:
let gradient = CAGradientLayer()
let sizeLength = UIScreen.mainScreen().bounds.size.height * 2
let defaultNavigationBarFrame = CGRectMake(0, 0, sizeLength, 64)
gradient.frame = defaultNavigationBarFrame
gradient.colors = [UIColor.whiteColor().CGColor, UIColor.blackColor().CGColor]
UINavigationBar.appearance().setBackgroundImage(self.image(fromLayer: gradient), forBarMetrics: .Default)
For creating image from layer:
func image(fromLayer layer: CALayer) -> UIImage {
UIGraphicsBeginImageContext(layer.frame.size)
layer.renderInContext(UIGraphicsGetCurrentContext()!)
let outputImage = UIGraphicsGetImageFromCurrentImageContext()
UIGraphicsEndImageContext()
return outputImage!
}
This is the solution without using an intermediate CAGradientLayer, and just using CoreGraphics, in Swift 3.0.
Essentially, the method creates a UIImage on the fly with the gradient colors passed and sets it.
extension UINavigationBar
{
/// Applies a background gradient with the given colors
func apply(gradient colors : [UIColor]) {
var frameAndStatusBar: CGRect = self.bounds
frameAndStatusBar.size.height += 20 // add 20 to account for the status bar
setBackgroundImage(UINavigationBar.gradient(size: frameAndStatusBar.size, colors: colors), for: .default)
}
/// Creates a gradient image with the given settings
static func gradient(size : CGSize, colors : [UIColor]) -> UIImage?
{
// Turn the colors into CGColors
let cgcolors = colors.map { $0.cgColor }
// Begin the graphics context
UIGraphicsBeginImageContextWithOptions(size, true, 0.0)
// If no context was retrieved, then it failed
guard let context = UIGraphicsGetCurrentContext() else { return nil }
// From now on, the context gets ended if any return happens
defer { UIGraphicsEndImageContext() }
// Create the Coregraphics gradient
var locations : [CGFloat] = [0.0, 1.0]
guard let gradient = CGGradient(colorsSpace: CGColorSpaceCreateDeviceRGB(), colors: cgcolors as NSArray as CFArray, locations: &locations) else { return nil }
// Draw the gradient
context.drawLinearGradient(gradient, start: CGPoint(x: 0.0, y: 0.0), end: CGPoint(x: size.width, y: 0.0), options: [])
// Generate the image (the defer takes care of closing the context)
return UIGraphicsGetImageFromCurrentImageContext()
}
}
The defer statement makes this so much clean than prior versions.
Be noted that CGGradient are available since iOS 8.0.
Also, this creates the gradient from left to right, tweaking the parameters of drawLinearGradient (start and end) moves the locations. This is up for your implementation.
For Swift 4.2
extension UINavigationBar {
func setGradientBackground(colors: [Any]) {
let gradient: CAGradientLayer = CAGradientLayer()
gradient.locations = [0.0 , 0.5, 1.0]
gradient.startPoint = CGPoint(x: 0.0, y: 1.0)
gradient.endPoint = CGPoint(x: 1.0, y: 1.0)
var updatedFrame = self.bounds
updatedFrame.size.height += self.frame.origin.y
gradient.frame = updatedFrame
gradient.colors = colors;
self.setBackgroundImage(self.image(fromLayer: gradient), for: .default)
}
func image(fromLayer layer: CALayer) -> UIImage {
UIGraphicsBeginImageContext(layer.frame.size)
layer.render(in: UIGraphicsGetCurrentContext()!)
let outputImage = UIGraphicsGetImageFromCurrentImageContext()
UIGraphicsEndImageContext()
return outputImage!
}
}
How to use
self.navigationController?.navigationBar.setGradientBackground(colors: [
UIColor.red.cgColor,
UIColor.green.cgColor,
UIColor.blue.cgColor
])