为什么UINavigationBar背景图片重复？

Question

图片大小为640 X 44，适用于iPad肖像。出于某种原因，它显示为图案图像而不是拉伸。

的iOS 6

Answer 1

的原因是，iPad的分辨率是1024x768.Thus，图像的宽度应为768

Answer 2

试试下面的伸展你的图像：

// 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 3

一种方法是根据导航栏的宽度调整图像的大小。

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)!] 

而对于调整图像的功能是：

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! 
    } 
}