以编程方式切换到TabBar选项卡视图？

Question

Let's say I have a UIButton in one tab view in my iPhone app, and I want to have it open a different tab in the tab bar of the TabBarController . How would I write the code to do this?

I'm assuming I unload the existing view and load a specific tab view, but I'm not sure how to write the code exactly.

Answer 1

Try this code in Swift or Objective-C

Swift

self.tabBarController.selectedIndex = 1

Objective-C

[self.tabBarController setSelectedIndex:1];

Answer 2

Note that the tabs are indexed starting from 0. So the following code snippet works

tabBarController = [[UITabBarController alloc] init];
.
.
.
tabBarController.selectedViewController = [tabBarController.viewControllers objectAtIndex:4];

goes to the fifth tab in the bar.

Answer 3

My opinion is that selectedIndex or using objectAtIndex is not necessarily the best way to switch the tab. If you reorder your tabs, a hard coded index selection might mess with your former app behavior.

If you have the object reference of the view controller you want to switch to, you can do:

tabBarController.selectedViewController = myViewController

Of course you must make sure, that myViewController really is in the list of tabBarController.viewControllers .

Answer 4

您只需将UITabBarController上的selectedIndex属性设置为适当的索引，就可以像用户点击选项卡按钮一样更改视图。

Answer 5

I tried what Disco S2 suggested, it was close but this is what ended up working for me. This was called after completing an action inside another tab.

for (UINavigationController *controller in self.tabBarController.viewControllers)
{
    if ([controller isKindOfClass:[MyViewController class]])
    {
        [self.tabBarController setSelectedViewController:controller];
        break;
    }
}

Answer 6

For cases where you may be moving the tabs, here is some code.

for ( UINavigationController *controller in self.tabBarController.viewControllers ) {
            if ( [[controller.childViewControllers objectAtIndex:0] isKindOfClass:[MyViewController class]]) {
                [self.tabBarController setSelectedViewController:controller];
                break;
            }
        }

Answer 7

I wanted to be able to specify which tab was shown by class rather than index as I thought it made for a robust solution that was less dependant on how you wire up IB. I didn't find either Disco's or Joped's solutions to work so i created this method:

-(void)setTab:(Class)class{
    int i = 0;
    for (UINavigationController *controller in self.tabBarContontroller.viewControllers){
        if ([controller isKindOfClass:class]){
            break;
        }
        i++;
    }
    self.tabBarContontroller.selectedIndex = i;
}

you call it like this:

[self setTab:[YourClass class]];

Hope this is helpful to someone

Answer 8

Like Stuart Clark's solution but for Swift 3:

func setTab<T>(_ myClass: T.Type) {
    var i: Int = 0
    if let controllers = self.tabBarController?.viewControllers {
        for controller in controllers {
            if let nav = controller as? UINavigationController, nav.topViewController is T {
                break
            }
            i = i+1
        }
    }
    self.tabBarController?.selectedIndex = i
}

Use it like this:

setTab(MyViewController.self)

Please note that my tabController links to viewControllers behind navigationControllers. Without navigationControllers it would look like this:

if let controller is T {

Answer 9

My issue is a little different, I need to switch from one childViewController in 1st tabBar to home viewController of 2nd tabBar. I simply use the solution provided in the upstairs:

tabBarController.selectedIndex = 2

However when it switched to the home page of 2nd tabBar, the content is invisible. And when I debug, viewDidAppear, viewWillAppear, viewDidLoad, none of them is called. My solutions is to add the following code in the UITabBarController:

override var shouldAutomaticallyForwardAppearanceMethods: Bool 
{
    return true
}

Answer 10

Use in AppDelegate.m file:

(void)tabBarController:(UITabBarController *)tabBarController
 didSelectViewController:(UIViewController *)viewController
{

     NSLog(@"Selected index: %d", tabBarController.selectedIndex);

    if (viewController == tabBarController.moreNavigationController)
    {
        tabBarController.moreNavigationController.delegate = self;
    }

    NSUInteger selectedIndex = tabBarController.selectedIndex;

    switch (selectedIndex) {

        case 0:
            NSLog(@"click me %u",self.tabBarController.selectedIndex);
            break;
        case 1:
            NSLog(@"click me again!! %u",self.tabBarController.selectedIndex);
            break;

        default:
            break;

    }

}

Answer 11

Like Stuart Clark's solution but for Swift 3 and using restoration identifier to find correct tab:

private func setTabById(id: String) {
  var i: Int = 0
  if let controllers = self.tabBarController?.viewControllers {
    for controller in controllers {
      if let nav = controller as? UINavigationController, nav.topViewController?.restorationIdentifier == id {
        break
      }
      i = i+1
    }
  }
  self.tabBarController?.selectedIndex = i
}

Use it like this ("Humans" and "Robots" must also be set in storyboard for specific viewController and it's Restoration ID, or use Storyboard ID and check "use storyboard ID" as restoration ID):

struct Tabs {
    static let Humans = "Humans"
    static let Robots = "Robots"
}
setTabById(id: Tabs.Robots)

Please note that my tabController links to viewControllers behind navigationControllers. Without navigationControllers it would look like this:

if controller.restorationIdentifier == id {

Answer 12

import UIKit

class TabbarViewController: UITabBarController,UITabBarControllerDelegate {

//MARK:- View Life Cycle

override func viewDidLoad() {
    super.viewDidLoad()

}

override func didReceiveMemoryWarning() {
    super.didReceiveMemoryWarning()

}

//Tabbar delegate method
override func tabBar(_ tabBar: UITabBar, didSelect item: UITabBarItem) {
    let yourView = self.viewControllers![self.selectedIndex] as! UINavigationController
    yourView.popToRootViewController(animated:false)
}



}