为什么UINavigationBar背景图像重复？

Question

图像尺寸为640 X 44，适用于iPad Portrait。由于某种原因，它显示为图案图像而不是拉伸。

iOS 6

Answer 1

尝试以下方法来拉伸您的图片：

// load the background image navbar.png
UIImage *imageNavBar = [UIImage imageNamed:@"navbar"];

// set the image as stretchable and set into navbar globally
imageNavBar = [imageNavBar stretchableImageWithLeftCapWidth:0 topCapHeight:0];
[[UINavigationBar appearance] setBackgroundImage:imageNavBar forBarMetrics:UIBarMetricsDefault];

Answer 2

原因是ipad的分辨率是1024x768。因此，你的图像宽度应为768

Answer 3

一种方法是根据导航栏的宽度调整图像大小。

let navBackgroundImage:UIImage! = UIImage(named: "top_header_iPhone")
let navimg = navBackgroundImage.resizeImageWith(newSize: CGSize(width: UIScreen.main.bounds.size.width, height: navBackgroundImage.size.height))

UINavigationBar .appearance().setBackgroundImage(navimg, for:.default)

UINavigationBar.appearance().titleTextAttributes = [ NSFontAttributeName: UIFont(name: "FightingSpiritturbo", size: 23)!]

调整图像大小的功能是：

extension UIImage{

    func resizeImageWith(newSize: CGSize) -> UIImage {

        let horizontalRatio = newSize.width / size.width
        let verticalRatio = newSize.height / size.height

        let ratio = max(horizontalRatio, verticalRatio)
        let newSize = CGSize(width: size.width * ratio, height: size.height * ratio)
        UIGraphicsBeginImageContextWithOptions(newSize, true, 0)
        draw(in: CGRect(origin: CGPoint(x: 0, y: 0), size: newSize))
        let newImage = UIGraphicsGetImageFromCurrentImageContext()
        UIGraphicsEndImageContext()
        return newImage!
    }
}