iOS：如何在 UITabBarItem 中添加下划线

Posted 2023-03-08

【中文标题】iOS：如何在 UITabBarItem 中添加下划线

【英文标题】：iOS : How to add Underline in UITabBarItem

【发布时间】：2015-09-19 13:30:53

【问题描述】：

我正在使用需要在UITabbarItem 中添加下划线的应用程序。

所以我想在 ios 的默认 UITabbarcontroller 中选择的 UITabbarItem 下添加下划线。

我已经创建了UITabbarcontroller 的子类，但没有找到任何添加行的方法。

我想做类似下图的事情。

如果有人对此有任何想法，请在此处分享。

【参考方案1】：

Swift 3 代码

在 didFininshLaunch 调用方法中：

func application(_ application: UIApplication, didFinishLaunchingWithOptions launchOptions: [UIApplicationLaunchOptionsKey: Any]?) -> Bool 
        // Override point for customization after application launch.
        UITabBar.appearance().selectionIndicatorImage = getImageWithColorPosition(color: UIColor.blue, size: CGSize(width:(self.window?.frame.size.width)!/4,height: 49), lineSize: CGSize(width:(self.window?.frame.size.width)!/4, height:2))
        return true
    

方法：

func getImageWithColorPosition(color: UIColor, size: CGSize, lineSize: CGSize) -> UIImage 
        let rect = CGRect(x:0, y: 0, width: size.width, height: size.height)
        let rectLine = CGRect(x:0, y:size.height-lineSize.height,width: lineSize.width,height: lineSize.height)
        UIGraphicsBeginImageContextWithOptions(size, false, 0)
        UIColor.clear.setFill()
        UIRectFill(rect)
        color.setFill()
        UIRectFill(rectLine)
        let image: UIImage = UIGraphicsGetImageFromCurrentImageContext()!
        UIGraphicsEndImageContext()
        return image
    

【讨论】：

你的代码帮了我很多..我需要更多的自定义，需要有一个左上角和右上角。我该怎么做

top 怎么办？我需要在所选 tabItem 的顶部显示该行。

【参考方案2】：

请试试这个。 我已经在我的应用程序中使用过一次，希望对您也有帮助。

这就是我以编程方式创建标签栏的方式：

      UITabBarController *tab = [[UITabBarController alloc]init];
      ViewController1 *v1 = [[ViewController1 alloc]init];
      ViewController1 *v2 = [[ViewController1 alloc]init];
      ViewController1 *v3 = [[ViewController1 alloc]init];
      ViewController1 *v4 = [[ViewController1 alloc]init];

      tab.viewControllers = [NSArray
arrayWithObjects:v1,v2,v3,v4,nil];

      [[tab.tabBar.items objectAtIndex:0]setImage:[UIImage imageNamed:@""]];
      [[tab.tabBar.items objectAtIndex:1]setImage:[UIImage imageNamed:@""]];
      [[tab.tabBar.items objectAtIndex:2]setImage:[UIImage imageNamed:@""]];
      [[tab.tabBar.items objectAtIndex:3]setImage:[UIImage imageNamed:@""]];
      int divide = 4;
      if([UIDevice currentDevice].userInterfaceIdiom ==UIUserInterfaceIdiomPad)
          divide =6;
      
      UIView *view = [[UIView alloc]initWithFrame:CGRectMake(tab.tabBar.frame.origin.x,tab.tabBar.frame.origin.y, self.view.frame.size.width/divide, 56)];

      UIImageView *border = [[UIImageView alloc]initWithFrame:CGRectMake(view.frame.origin.x,view.frame.size.height-6, self.view.frame.size.width/divide, 6)];  
      border.backgroundColor = “your color”;
      [view addSubview:border];
      [tab.tabBar setSelectionIndicatorImage:[self changeViewToImage:view]];

//This is the method that will draw the underline
-(UIImage ) changeViewToImage : (UIView ) viewForImage 
      UIGraphicsBeginImageContext(viewForImage.bounds.size);
      [viewForImage.layer   renderInContext:UIGraphicsGetCurrentContext()];
      UIImage *img = UIGraphicsGetImageFromCurrentImageContext();
      UIGraphicsEndImageContext();
      return img;

【参考方案3】：

只需将此代码放入 Appdelegate。

- (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions 
// Override point for customization after application launch.

UIView *view1 = [[UIView alloc]initWithFrame:CGRectMake([UITabBar appearance].frame.origin.x,[UITabBar appearance].frame.origin.y, [[UIScreen mainScreen] bounds].size.width/3, 56)];

UIImageView *border = [[UIImageView alloc]initWithFrame:CGRectMake(view1.frame.origin.x,view1.frame.size.height-6, [[UIScreen mainScreen] bounds].size.width/3, 6)];
border.backgroundColor = [UIColor colorWithRed:255.0f/255.0f green:105.0f/255.0f blue:84.0f/255.0f alpha:1.0f];
[view1 addSubview:border];
UIImage *img=[self ChangeViewToImage:view1];
[[UITabBar appearance] setSelectionIndicatorImage:img];
[[UITabBar appearance] setTintColor: [UIColor colorWithRed:255.0f/255.0f green:105.0f/255.0f blue:84.0f/255.0f alpha:1.0f]];

return YES;

-(UIImage * ) ChangeViewToImage : (UIView *) viewForImage

UIGraphicsBeginImageContext(viewForImage.bounds.size);
[viewForImage.layer renderInContext:UIGraphicsGetCurrentContext()];
UIImage *img = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
return img;

【参考方案4】：

在 AppDelegate 的 didFininshLaunch 方法中为 UITabbar 添加全局样式

UITabBar.appearance().selectionIndicatorImage = UIImage.getImageWithColorPosition(UIColor.whiteColor(), size: CGSizeMake(kScreenWidth/4, 49), lineSize: CGSizeMake(kScreenWidth/4, 2))

class func getImageWithColorPosition(color: UIColor, size: CGSize, lineSize: CGSize) -> UIImage 
    let rect = CGRectMake(0, 0, size.width, size.height)
    let rectLine = CGRectMake(0, size.height-lineSize.height, lineSize.width, lineSize.height)
    UIGraphicsBeginImageContextWithOptions(size, false, 0)
    UIColor.clearColor().setFill()
    UIRectFill(rect)
    color.setFill()
    UIRectFill(rectLine)
    let image: UIImage = UIGraphicsGetImageFromCurrentImageContext()
    UIGraphicsEndImageContext()
    return image

编辑 Swift 3

func getImageWithColorPosition(color: UIColor, size: CGSize, lineSize: CGSize) -> UIImage 

    let rect = CGRect(x: 0, y: 0, width: size.width, height: size.height)
    let rectLine = CGRect(x: 0, y: size.height-lineSize.height, width: lineSize.width, height: lineSize.height)
    UIGraphicsBeginImageContextWithOptions(size, false, 0)
    UIColor.clear.setFill()
    UIRectFill(rect)
    color.setFill()
    UIRectFill(rectLine)
    let image = UIGraphicsGetImageFromCurrentImageContext()!
    UIGraphicsEndImageContext()
    return image

【参考方案5】：

使用此代码为任何UIView 对象添加底部边框，只需将view 替换为您的UITabbarItem 对象即可：

CALayer *bottomBorder = [CALayer layer];
bottomBorder.frame = CGRectMake(0, view.frame.size.height - 1, view.frame.size.width - 1, 1);
bottomBorder.backgroundColor = [UIColor lightGrayColor].CGColor;
[view.layer addSublayer:bottomBorder];

【讨论】：

您自己检查过这个解决方案吗？ UITabBarItem 不继承自 UIView 并且没有 layer 属性。