blocks|key|740972|text|您只需将UITabBarController上的selectedIndex属性设置为适当的索引，视图就会更改，就像用户单击选项卡按钮一样。|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|740973|entityMap^0|O|D|0^^$0|@$1|2|3|4|5|6|7|H|8|@$9|I|A|J|B|C]]|D|@]|E|$]]|$1|F|3|-4|5|6|7|K|8|@]|D|@]|E|$]]]|G|$]]

You can simply just set the <code>selectedIndex</code> property on the UITabBarController to the appropriate index and the view will be changed just like the user tapped the tab button.

blocks|key|741053|text|请注意，制表符从0开始编制索引。因此，下面的代码片段可以正常工作|type|unstyled|depth|inlineStyleRanges|entityRanges|data|741054|tabBarController+=+[[UITabBarController+alloc]+init];
.
.
.
tabBarController.selectedViewController+=+[tabBarController.viewControllers+objectAtIndex:4];|code-block|syntax|javascript|741055|转到栏中的第五个选项卡。|741056|entityMap^0|0|0|0^^$0|@$1|2|3|4|5|6|7|K|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|L|8|@]|9|@]|A|$E|F]]|$1|G|3|H|5|6|7|M|8|@]|9|@]|A|$]]|$1|I|3|-4|5|6|7|N|8|@]|9|@]|A|$]]]|J|$]]

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

<pre><code>tabBarController = [[UITabBarController alloc] init];
.
.
.
tabBarController.selectedViewController = [tabBarController.viewControllers objectAtIndex:4];
</code></pre>

goes to the fifth tab in the bar.

blocks|key|956990|text|我的观点是，使用selectedIndex或使用objectAtIndex不一定是切换选项卡的最佳方式。如果你重新排序你的标签，一个硬编码的索引选择可能会扰乱你以前的应用行为。|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|956991|如果您有要切换到的视图控制器的对象引用，则可以执行以下操作：|956992|tabBarController.selectedViewController+=+myViewController|code-block|syntax|javascript|956993|当然，您必须确保myViewController确实在tabBarController.viewControllers列表中。|956994|entityMap^0|8|D|O|D|0|0|0|8|G|R|W|0^^$0|@$1|2|3|4|5|6|7|Q|8|@$9|R|A|S|B|C]|$9|T|A|U|B|C]]|D|@]|E|$]]|$1|F|3|G|5|6|7|V|8|@]|D|@]|E|$]]|$1|H|3|I|5|J|7|W|8|@]|D|@]|E|$K|L]]|$1|M|3|N|5|6|7|X|8|@$9|Y|A|Z|B|C]|$9|10|A|11|B|C]]|D|@]|E|$]]|$1|O|3|-4|5|6|7|12|8|@]|D|@]|E|$]]]|P|$]]

My opinion is that <code>selectedIndex</code> or using <code>objectAtIndex</code> 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:

<pre><code>tabBarController.selectedViewController = myViewController
</code></pre>

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

blocks|key|741152|text|对于可能要移动选项卡的情况，这里有一些代码。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|741153|for+(+UINavigationController+*controller+in+self.tabBarController.viewControllers+)+{
++++++++++++if+(+[[controller.childViewControllers+objectAtIndex:0]+isKindOfClass:[MyViewController+class]])+{
++++++++++++++++[self.tabBarController+setSelectedViewController:controller];
++++++++++++++++break;
++++++++++++}
++++++++}|code-block|syntax|javascript|741154|entityMap^0|0|0^^$0|@$1|2|3|4|5|6|7|I|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|J|8|@]|9|@]|A|$E|F]]|$1|G|3|-4|5|6|7|K|8|@]|9|@]|A|$]]]|H|$]]

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

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

blocks|key|741191|text|我尝试了迪斯科S2的建议，很接近，但这就是最终对我有效的方法。这是在完成另一个选项卡中的操作后调用的。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|741192|for+(UINavigationController+*controller+in+self.tabBarController.viewControllers)
{
++++if+([controller+isKindOfClass:[MyViewController+class]])
++++{
++++++++[self.tabBarController+setSelectedViewController:controller];
++++++++break;
++++}
}|code-block|syntax|javascript|741193|entityMap^0|0|0^^$0|@$1|2|3|4|5|6|7|I|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|J|8|@]|9|@]|A|$E|F]]|$1|G|3|-4|5|6|7|K|8|@]|9|@]|A|$]]]|H|$]]

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.

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

blocks|key|957104|text|我希望能够指定哪个选项卡是按类显示的，而不是按索引显示的，因为我认为这是一个健壮的解决方案，不太依赖于您如何连接IB。我没有找到迪斯科或Joped的解决方案，所以我创建了这个方法：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|957105|-(void)setTab:(Class)class{
++++int+i+=+0;
++++for+(UINavigationController+*controller+in+self.tabBarContontroller.viewControllers){
++++++++if+([controller+isKindOfClass:class]){
++++++++++++break;
++++++++}
++++++++i%2B%2B;
++++}
++++self.tabBarContontroller.selectedIndex+=+i;
}|code-block|syntax|javascript|957106|你可以这样称呼它：|957107|[self+setTab:[YourClass+class]];|957108|希望这对某些人有帮助|957109|entityMap^0|0|0|0|0|0^^$0|@$1|2|3|4|5|6|7|O|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|P|8|@]|9|@]|A|$E|F]]|$1|G|3|H|5|6|7|Q|8|@]|9|@]|A|$]]|$1|I|3|J|5|D|7|R|8|@]|9|@]|A|$E|F]]|$1|K|3|L|5|6|7|S|8|@]|9|@]|A|$]]|$1|M|3|-4|5|6|7|T|8|@]|9|@]|A|$]]]|N|$]]

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:

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

you call it like this:

<pre><code>[self setTab:[YourClass class]];
</code></pre>

Hope this is helpful to someone

blocks|key|741234|text|在AppDelegate.m文件中使用：|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|741235|(void)tabBarController:(UITabBarController+*)tabBarController
+didSelectViewController:(UIViewController+*)viewController
{

+++++NSLog(@"Selected+index:+%25d",+tabBarController.selectedIndex);

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

++++NSUInteger+selectedIndex+=+tabBarController.selectedIndex;

++++switch+(selectedIndex)+{

++++++++case+0:
++++++++++++NSLog(@"click+me+%25u",self.tabBarController.selectedIndex);
++++++++++++break;
++++++++case+1:
++++++++++++NSLog(@"click+me+again!!+%25u",self.tabBarController.selectedIndex);
++++++++++++break;

++++++++default:
++++++++++++break;

++++}

}|code-block|syntax|javascript|741236|entityMap^0|1|D|0|0^^$0|@$1|2|3|4|5|6|7|M|8|@$9|N|A|O|B|C]]|D|@]|E|$]]|$1|F|3|G|5|H|7|P|8|@]|D|@]|E|$I|J]]|$1|K|3|-4|5|6|7|Q|8|@]|D|@]|E|$]]]|L|$]]

Use in <code>AppDelegate.m</code> file:

<pre><code>(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;

 }

}
</code></pre>

blocks|key|741276|text|就像Stuart+Clark的解决方案，但对于Swift+3：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|741277|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%2B1
++++++++}
++++}
++++self.tabBarController?.selectedIndex+=+i
}|code-block|syntax|javascript|741278|像这样使用它：|741279|setTab(MyViewController.self)|741280|请注意，我的tabController链接到navigationControllers后面的viewControllers。如果没有navigationControllers，它将如下所示：|741281|if+let+controller+is+T+{|741282|entityMap^0|0|0|0|0|0|0^^$0|@$1|2|3|4|5|6|7|Q|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|R|8|@]|9|@]|A|$E|F]]|$1|G|3|H|5|6|7|S|8|@]|9|@]|A|$]]|$1|I|3|J|5|D|7|T|8|@]|9|@]|A|$E|F]]|$1|K|3|L|5|6|7|U|8|@]|9|@]|A|$]]|$1|M|3|N|5|D|7|V|8|@]|9|@]|A|$E|F]]|$1|O|3|-4|5|6|7|W|8|@]|9|@]|A|$]]]|P|$]]

Like Stuart Clark's solution but for Swift 3:

<pre><code>func setTab&lt;T&gt;(_ 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
}
</code></pre>

Use it like this:

<pre><code>setTab(MyViewController.self)
</code></pre>

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

<pre><code>if let controller is T {
</code></pre>

blocks|key|741334|text|与Stuart+Clark的解决方案类似，但适用于Swift+3，并使用恢复标识符来查找正确的选项卡：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|741335|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%2B1
++++}
++}
++self.tabBarController?.selectedIndex+=+i
}|code-block|syntax|javascript|741336|这样使用(“Human”和"Robots“也必须在故事板中为特定的viewController和它的还原ID进行设置，或者使用故事板ID并选中"use+storyboard+ID”作为还原ID)：|741337|struct+Tabs+{
++++static+let+Humans+=+"Humans"
++++static+let+Robots+=+"Robots"
}
setTabById(id:+Tabs.Robots)|741338|请注意，我的tabController链接到navigationControllers后面的viewControllers。如果没有navigationControllers，它将如下所示：|741339|if+controller.restorationIdentifier+==+id+{|741340|entityMap^0|0|0|0|0|0|0^^$0|@$1|2|3|4|5|6|7|Q|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|R|8|@]|9|@]|A|$E|F]]|$1|G|3|H|5|6|7|S|8|@]|9|@]|A|$]]|$1|I|3|J|5|D|7|T|8|@]|9|@]|A|$E|F]]|$1|K|3|L|5|6|7|U|8|@]|9|@]|A|$]]|$1|M|3|N|5|D|7|V|8|@]|9|@]|A|$E|F]]|$1|O|3|-4|5|6|7|W|8|@]|9|@]|A|$]]]|P|$]]

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

<pre><code>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
}
</code></pre>

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):

<pre><code>struct Tabs {
 static let Humans = "Humans"
 static let Robots = "Robots"
}
setTabById(id: Tabs.Robots)
</code></pre>

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

<pre><code>if controller.restorationIdentifier == id {
</code></pre>

blocks|key|741347|text|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)
}



}|type|code-block|depth|inlineStyleRanges|entityRanges|data|syntax|javascript|741348|unstyled|entityMap^0|0^^$0|@$1|2|3|4|5|6|7|G|8|@]|9|@]|A|$B|C]]|$1|D|3|-4|5|E|7|H|8|@]|9|@]|A|$]]]|F|$]]

<pre><code>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)
}



}
</code></pre>

blocks|key|957342|text|我的问题有点不同，我需要从第一个tabBar中的一个childViewController切换到第二个viewController中的主tabBar。我只是简单地使用了上面提供的解决方案：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|957343|tabBarController.selectedIndex+=+2|code-block|syntax|javascript|957344|然而，当它切换到switched的主页时，内容是看不见的。当我调试viewDidAppear、viewWillAppear、viewDidLoad时，它们都不会被调用。我的解决方案是在UITabBarController中添加以下代码：|957345|override+var+shouldAutomaticallyForwardAppearanceMethods:+Bool+
{
++++return+true
}|957346|entityMap^0|0|0|0|0^^$0|@$1|2|3|4|5|6|7|M|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|N|8|@]|9|@]|A|$E|F]]|$1|G|3|H|5|6|7|O|8|@]|9|@]|A|$]]|$1|I|3|J|5|D|7|P|8|@]|9|@]|A|$E|F]]|$1|K|3|-4|5|6|7|Q|8|@]|9|@]|A|$]]]|L|$]]

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:

<pre><code>tabBarController.selectedIndex = 2
</code></pre>

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:

<pre><code>override var shouldAutomaticallyForwardAppearanceMethods: Bool 
{
 return true
}
</code></pre>

Let's say I have a <code>UIButton</code> in one tab view in my iPhone app, and I want to have it open a different tab in the tab bar of the <code>TabBarController</code>. 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.

Switching to a TabBar tab view programmatically?

Swift

假设我在iPhone应用程序的一个选项卡视图中有一个UIButton，我想让它在TabBarController的选项卡栏中打开另一个选项卡。我该如何编写代码来做到这一点呢？我假设我卸载了现有的视图并加载了一个特定的选项卡视图，但是我不确定如何准确地编写代码。

问以编程方式切换到TabBar选项卡视图？
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