按需重新加载UITabBarController
按需重新加载UITabBarController
提问于 2019-08-27 19:27:53
我有以下两个项目的TabBarController。这是正确的表现。
当setupItems()更改其值时，我将从另一个控制器调用something函数。
函数被正确调用，问题是navFirstController.tabBarItem.image没有被更新。
class TabBarController: UITabBarController {
override func viewDidLoad() {
super.viewDidLoad()
setupItems()
}
func setupItems() {
let scale: CGFloat = 0.35
let navFirstController = UINavigationController(rootViewController: FirstController())
let navSecondController = UINavigationController(rootViewController: SecondController())
navSecondController.tabBarItem.image = UIImage.scale(image: UIImage(named: "image2")!, by: scale)
navSecondController.tabBarItem.imageInsets = UIEdgeInsets(top: 8, left: 0, bottom: -8, right: 0)
if something == true {
navFirstController.tabBarItem.image = UIImage.scale(image: UIImage(named: "image1")!, by: scale)
} else {
navFirstController.tabBarItem.image = UIImage.scale(image: UIImage(named: "image3")!, by: scale)
}
navFirstController.tabBarItem.imageInsets = UIEdgeInsets(top: 8, left: 0, bottom: -8, right: 0)
viewControllers = [navSecondController, navFirstController]
}
}我试过：
1) viewControllers?.remove(at: 1)在setupItems()的开头
2) navFirstController.removeFromParent()在setupItems()的开头
3) self.viewWillLayoutSubviews()在setupItems()的末尾
4) self.view.setNeedsLayout()，self.view.setNeedsDisplay()在setupItems()的末尾
回答 2
Stack Overflow用户
发布于 2019-08-30 10:51:00
我不认为我们需要再次创建viewControllers对象，仅仅是为了更改选项卡条图像。我们只需要从viewController数组中获取viewControllers对象并更改图像。
class ViewController: UIViewController {
override func viewDidLoad() {
super.viewDidLoad()
// Do any additional setup after loading the view.
}
}
class SecondViewController: UIViewController {
override func viewDidLoad() {
super.viewDidLoad()
}
@IBAction func btnClicked(_ sender: Any) {
//change image of tab bar item on button clicked
if let tabVC = self.tabBarController as? TabBarController {
tabVC.changeImage()
}
}
}
class TabBarController: UITabBarController {
override func viewDidLoad() {
super.viewDidLoad()
setupItems()
}
func setupItems() {
let storyboard = UIStoryboard(name: "Main", bundle: Bundle.main)
let firstVC = storyboard.instantiateViewController(withIdentifier: "First")
let navFirstController = UINavigationController(rootViewController: firstVC)
navFirstController.tabBarItem.image = UIImage(named: "Image1")
let secondVC = storyboard.instantiateViewController(withIdentifier: "Second")
let navSecondController = UINavigationController(rootViewController: secondVC)
navSecondController.tabBarItem.image = UIImage(named: "Image2")
viewControllers = [navSecondController, navFirstController]
}
func changeImage() {
if let second = viewControllers?[1] as? UINavigationController {
second.tabBarItem.selectedImage = UIImage(named: "Image3")
second.tabBarItem.image = UIImage(named: "Image3")
}
}
}如果要更改选定的选项卡项图像，则更改“”值，否则更改"selectedImage“值。
Stack Overflow用户
发布于 2019-08-30 17:11:54
您可能需要将图像的呈现模式设置为UIImageRenderingModeAlwaysOriginal。
试着改变这个：
navFirstController.tabBarItem.image = UIImage.scale(image: UIImage(named: "image1")!, by: scale)在这方面：
navFirstController.tabBarItem.image = UIImage.scale(image: UIImage(named: "image1")!, by: scale).withRenderingMode(.alwaysOriginal)编辑-示例代码
考虑一下这个设置：
- 初始视图控制器是一个自定义类TabBarViewController。
- 红色背景视图控制器是一个具有故事板ID "First“的UIViewController。
- 橙色背景视图控制器是一个自定义类SecondViewController，具有IBAction和情节提要ID "Second“。
Assets.xcassets文件有三个映像(40x40PNG)：
TabBarViewController
import UIKit
class TabBarViewController: UITabBarController {
var something: Bool = false
override func viewDidLoad() {
super.viewDidLoad()
setupItems()
}
override func viewDidAppear(_ animated: Bool) {
super.viewDidAppear(animated)
}
func setupItems() {
let storyboard = UIStoryboard(name: "Main", bundle: Bundle.main)
let firstVC = storyboard.instantiateViewController(withIdentifier: "First")
let navFirstController = UINavigationController(rootViewController: firstVC)
navFirstController.tabBarItem.image = UIImage(named: "image1")!.withRenderingMode(.alwaysOriginal)
let secondVC = storyboard.instantiateViewController(withIdentifier: "Second")
let navSecondController = UINavigationController(rootViewController: secondVC)
navSecondController.tabBarItem.image = UIImage(named: "image2")!.withRenderingMode(.alwaysOriginal)
navSecondController.tabBarItem.imageInsets = UIEdgeInsets(top: 8, left: 0, bottom: -8, right: 0)
if something == true {
navFirstController.tabBarItem.image = UIImage(named: "image3")!.withRenderingMode(.alwaysOriginal)
} else {
navFirstController.tabBarItem.image = UIImage(named: "image1")!.withRenderingMode(.alwaysOriginal)
}
navFirstController.tabBarItem.imageInsets = UIEdgeInsets(top: 8, left: 0, bottom: -8, right: 0)
viewControllers = [navSecondController, navFirstController]
}
}SecondViewController
import Foundation
import UIKit
class SecondViewController: UIViewController {
override func viewDidLoad() {
super.viewDidLoad()
}
@IBAction func btnClicked(_ sender: Any) {
//change image of tab bar item on button clicked
if let tabVC = self.tabBarController as? TabBarViewController {
tabVC.something = !tabVC.something
tabVC.setupItems()
}
}
}输出
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原文链接：
https://stackoverflow.com/questions/57681102
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