对于Uiimageview,如何在ios swift4中将CGgradient背景色设置为背景色?

您可以从渐变创建图像并将其设置为 imageView

let gradient = CAGradientLayer()
let screenWidth = UIScreen.main.bounds.size.width
let defaultNavigationBarFrame = CGRect(x: 0, y: 0, width: screenWidth, height: 64)
gradient.frame = defaultNavigationBarFrame

//colors
let gradientDark = UIColor(red: 148/255.0, green:210/255.0, blue: 245/255.0, alpha: 1.0)
let gradientLight = UIColor(red: 222/255.0, green:247/255.0, blue: 230/255.0, alpha: 1.0)
let gradientLight1 = UIColor(red: 245/255.0, green:247/255.0, blue: 206/255.0, alpha: 1.0)

gradient.colors = [gradientDark.cgColor,gradientLight.cgColor,gradientLight1.cgColor]
// Create image.
let imageBG: UIImage = self.gradientImage(fromLayer: gradient)

如果要在导航栏中进行设置。

self.navigationController?.navigationBar.setBackgroundImage(imageBG,
                                                                for: .default)

从渐变创建图像。

func gradientImage(fromLayer layer: CALayer) -> UIImage {
    UIGraphicsBeginImageContext(layer.frame.size)

    layer.render(in: UIGraphicsGetCurrentContext()!)

    let outputImage = UIGraphicsGetImageFromCurrentImageContext()

    UIGraphicsEndImageContext()

    return outputImage!
}