如何让UITabBar选择指示器图像填满整个space？

Question

我有一个 UITabBarController，我在其中使用此代码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

但是图像没有填满整个图像space - 见下图：

图像只是一个解决方案为 82x49px 的红色方块，但使用更宽的图像仍然无法填满整个 space。希望大家能帮忙～谢谢。

Answer 1

你应该看看 this 使 tabbarbgtest.png 可调整大小，然后将图像分配给 selectionIndicatorImage，你甚至可以在故事板编辑器中执行此操作。

Answer 2

如果你想在选项卡选择上设置红色图像，我会建议你设置活动选项卡栏项目的背景颜色，根据我的意见，每当你可以用编码做你的事情时，为什么要使用图像这样更好设置选择颜色而不是图像。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 UIImage 的以下扩展：

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
    }
}

希望对你有所帮助。

或这里有另一种方式：

在您的 tabBarController 中，您可以设置默认的 UITabBar tintColor、barTintColor、selectionIndicatorImage（这里有点作弊）和图像的渲染模式，请参阅下面的评论：

    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)
        }
    }
    }
    ...
}

并且您需要扩展 UIImage class 以制作具有您需要的大小的纯色图像：

 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!
    }
}

Answer 3

截至 2017 年，老实说 Piyush 的回答对我不起作用。在寻找另一个解决方案几天后，我找到了我的 - by subclassing the UITabBarController.

即使旋转也适用于多个设备。

备注:

将图像的渲染模式设置为Original。

将下面的 class 分配给 Storyboard 中的 UITabBarController 或作为基础 class 如果您正在以编程方式处理屏幕。

//
//  BaseTabBarController.swift
//  MyApp
//
//  Created by DRC on 1/27/17.
//  Copyright © 2017 PrettyITGirl. All rights reserved.
//

import UIKit

class BaseTabBarController: UITabBarController {

    let numberOfTabs: CGFloat = 4
    let tabBarHeight: CGFloat = 60

    override func viewWillAppear(_ animated: Bool) {
        super.viewWillAppear(animated)

        updateSelectionIndicatorImage()
    }

    override func viewWillLayoutSubviews() {
        super.viewWillLayoutSubviews()

        updateSelectionIndicatorImage()
    }

    func updateSelectionIndicatorImage() {
        let width = tabBar.bounds.width
        var selectionImage = UIImage(named:"myimage.png")
        let tabSize = CGSize(width: width/numberOfTabs, height: tabBarHeight)

        UIGraphicsBeginImageContext(tabSize)
        selectionImage?.draw(in: CGRect(x: 0, y: 0, width: tabSize.width, height: tabSize.height))
        selectionImage = UIGraphicsGetImageFromCurrentImageContext()
        UIGraphicsEndImageContext()

        tabBar.selectionIndicatorImage = selectionImage
    }

}

Answer 4

要支持 iPhone X（以下代码适用于所有版本），请在 viewDidLayoutSubviews() 中编写代码。

override func viewDidLayoutSubviews() {
    super.viewDidLayoutSubviews()
    let tabWidth = (tabBar.frame.width/CGFloat(tabBar.items!.count))
    let tabHeight = tabBar.frame.height
    self.tabBar.selectionIndicatorImage = imageWithColor(color: UIColor.white, size: CGSize(width: tabWidth, height: tabHeight)).resizableImage(withCapInsets: UIEdgeInsets(top: 0, left: 0, bottom: 0, right: 0))
 }

来源：https://github.com/Ramotion/animated-tab-bar/issues/191

Answer 5

objective c 中这个相对简单的解决方案适用于 iPhone X，不难转换为 swift:

CGFloat bottomPadding = 0;

if (@available(iOS 11.0, *)) {
  UIWindow *window = UIApplication.sharedApplication.keyWindow;
  bottomPadding = window.safeAreaInsets.bottom;
}

[UITabBar.appearance setSelectionIndicatorImage:[UIImage imageWithColor:[UIColor lightGrayColor] 
          andBounds:CGRectMake(0, 0, self.tabBar.frame.size.width/5, self.tabBar.frame.size.height + bottomPadding)]];

Answer 6

这是对上面的改编...

    import UIKit

    class BaseTabBarController: UITabBarController {

        var tabBarBounds: CGRect? {
            didSet {
                guard tabBarBounds != oldValue else { return }
                updateSelectionIndicatorColor(UIColor.green)
            }
        }

        override func viewWillLayoutSubviews() {
            super.viewWillLayoutSubviews()
            tabBarBounds = tabBar.bounds
        }

        func updateSelectionIndicatorColor(_ tintColor: UIColor) {
            guard let tabBarItems = self.tabBar.items else { return }

            let tabWidth = tabBar.bounds.width
            let tabHeight = tabBar.bounds.height
            let tabSize = CGSize(width: tabWidth / CGFloat(tabBarItems.count), height: tabHeight)
            var selectionImage = UIImage(color: tintColor, size: tabSize)

            UIGraphicsBeginImageContext(tabSize)
            selectionImage?.draw(in: CGRect(x: 0, y: 0, width: tabSize.width, height: tabSize.height))
            selectionImage = UIGraphicsGetImageFromCurrentImageContext()
            UIGraphicsEndImageContext()

            tabBar.selectionIndicatorImage = selectionImage
        }

    }

    public extension UIImage {
        public convenience init?(color: UIColor, size: CGSize = CGSize(width: 1, height: 1)) {
            let rect = CGRect(origin: .zero, size: size)
            UIGraphicsBeginImageContextWithOptions(rect.size, false, 0.0)
            color.setFill()
            UIRectFill(rect)
            let image = UIGraphicsGetImageFromCurrentImageContext()
            UIGraphicsEndImageContext()

            guard let cgImage = image?.cgImage else { return nil }
            self.init(cgImage: cgImage)
        }
    }

如何让UITabBar选择指示器图像填满整个space？

how to make UITabBar selection indicator image fill the whole space?

uitabbarcontroller

uiimage

ios

swift