小编典典

如何使UITabBar选择指示器图像填充整个空间?

swift

我有一个UITabBarController,在其中使用此代码来设置选择指示器图像:

let selectedBG = UIImage(named:"tabbarbgtest.png")?.resizableImageWithCapInsets(UIEdgeInsetsMake(0, 0, 0, 0))
UITabBar.appearance().selectionIndicatorImage = selectedBG

但是该图像不能填充整个空间-请参见下图:

在此处输入图片说明

图像只是一个红色的正方形,分辨率为82x49px,但是图像较宽时,它仍然无法填充整个空间。希望你们能提供帮助-谢谢。


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2020-07-07

共1个答案

小编典典

如果要在选项卡选择上设置红色图像,我建议您设置活动的选项卡栏项目的背景颜色,根据我的意见,只要您可以使用编码进行编码,为什么要使用图像,因此最好设置选择颜色,而不是图片。您可以使用以下代码来实现。

    // set red as selected background color
    let numberOfItems = CGFloat(tabBar.items!.count)
    let tabBarItemSize = CGSize(width: tabBar.frame.width / numberOfItems, height: tabBar.frame.height)
    tabBar.selectionIndicatorImage = UIImage.imageWithColor(color: UIColor.red, size: tabBarItemSize).resizableImage(withCapInsets: .zero)

    // remove default border
    tabBar.frame.size.width = self.view.frame.width + 4
    tabBar.frame.origin.x = -2

利用以下扩展UIImage

extension UIImage {
    class func imageWithColor(color: UIColor, size: CGSize) -> UIImage {
        let rect: CGRect = CGRect(x: 0, y: 0, width: size.width, height: size.height)
        UIGraphicsBeginImageContextWithOptions(size, false, 0)
        color.setFill()
        UIRectFill(rect)
        let image: UIImage = UIGraphicsGetImageFromCurrentImageContext()!
        UIGraphicsEndImageContext()
        return image
    }
}

希望对您有所帮助。

其他方式:

在您的tabBarController中,您可以设置图像的默认UITabBar
tintColor,barTintColor,selectionIndicatorImage(在此处作一些说明)和renderingMode,请参见以下注释:

    class MyTabBarController: UITabBarController, UINavigationControllerDelegate {
    ...
    override func viewDidLoad() {
        ...
            // Sets the default color of the icon of the selected UITabBarItem and Title
            UITabBar.appearance().tintColor = UIColor.red
        // Sets the default color of the background of the UITabBar
        UITabBar.appearance().barTintColor = UIColor.black

        // Sets the background color of the selected UITabBarItem (using and plain colored UIImage with the width = 1/5 of the tabBar (if you have 5 items) and the height of the tabBar)
        UITabBar.appearance().selectionIndicatorImage = UIImage().makeImageWithColorAndSize(color: UIColor.blue, size: CGSize(width: tabBar.frame.width/5, height: tabBar.frame.height))

        // Uses the original colors for your images, so they aren't not rendered as grey automatically.
        for item in (self.tabBar.items)! {
        if let image = item.image {
            item.image = image.withRenderingMode(.alwaysOriginal)
        }
    }
    }
    ...
}

您将需要扩展UIImage类,以制作具有所需大小的纯色图像:

 extension UIImage {
    func makeImageWithColorAndSize(color: UIColor, size: CGSize) -> UIImage {
        UIGraphicsBeginImageContextWithOptions(size, false, 0)
        color.setFill()
        UIRectFill(CGRect(x: 0, y: 0, width: size.width, height: size.height))
        let image = UIGraphicsGetImageFromCurrentImageContext()
        UIGraphicsEndImageContext()
        return image!
    }
}
2020-07-07