Xamarin.Forms Android 底部导航栏

在Android中常见设计底部导航栏，在Xamarin.Forms中如何实现该效果呢？

这里借助第三方框架来实现底部导航效果：

第三方库：Naxam.BottomTabbedPage

GitHub地址：https://github.com/naxam/bottomtabbedpage-xamarin-forms

首先：创建MainTabAndroidPage继承于BottomTabbedPage

 1 using Naxam.Controls.Forms;
 2 using System;
 3 using System.Collections.Generic;
 4 using System.Diagnostics;
 5 using System.Linq;
 6 using System.Text;
 7 using System.Threading.Tasks;
 8 
 9 using Xamarin.Forms;
10 using Xamarin.Forms.Xaml;
11 
12 namespace XFPractice.Pages.MainTab
13 {
14     [XamlCompilation(XamlCompilationOptions.Compile)]
15     public partial class MainTabAndroidPage : BottomTabbedPage
16     {
17         public MainTabAndroidPage()
18         {
19             InitializeComponent();
20             NavigationPage.SetHasNavigationBar(this, true);
21             NavigationPage.SetHasBackButton(this,false);
22             InitTabPages();
23 
24             this.Appearing += MainTabAndroidPage_Appearing;
25             this.CurrentPageChanged += MainTabAndroidPage_CurrentPageChanged;
26         }
27 
28         private void MainTabAndroidPage_Appearing(object sender, EventArgs e)
29         {
30             UpdateNavigationBar();
31         }
32 
33         private void MainTabAndroidPage_CurrentPageChanged(object sender, System.EventArgs e)
34         {
35             UpdateNavigationBar();
36         }
37 
38         private void UpdateNavigationBar()
39         {
40             Title = CurrentPage.Title;
41         }
42 
43         private void InitTabPages()
44         {
45             this.Children.Add(new MessagePage() { Title = "消息", Icon = "icon_chat" });
46             this.Children.Add(new ContactsPage() { Title = "通讯录", Icon = "icon_org" });
47             this.Children.Add(new WorkStagePage() { Title = "工作台", Icon = "icon_table" });
48             this.Children.Add(new ProfilePage() { Title = "我", Icon = "icon_me" });
49         }
50 
51 
52     }
53 }

View Code

Xaml代码：

<?xml version="1.0" encoding="utf-8" ?>
<naxam:BottomTabbedPage xmlns="http://xamarin.com/schemas/2014/forms"
             xmlns:x="http://schemas.microsoft.com/winfx/2009/xaml"
             xmlns:naxam="clr-namespace:Naxam.BottomNavs.Forms;assembly=Naxam.BottomNavs.Forms"
             x:Class="XFPractice.Pages.MainTab.MainTabAndroidPage">
   
</naxam:BottomTabbedPage>

View Code

仅仅是以上代码还不足以达到我们期望的效果，还需要在MainActivity中添加如下代码，并在OnCreate中调用：

void SetupBottomTabs()
        {
            var stateList = new Android.Content.Res.ColorStateList(
                new int[][] {
                    new int[] { Android.Resource.Attribute.StateChecked
                },
                new int[] { Android.Resource.Attribute.StateEnabled
                }
                },
                new int[] {
                    Color.Red, //Selected
                    Color.White //Normal
                });
            
            BottomTabbedRenderer.BackgroundColor = new Color(0x9C, 0x27, 0xB0);
            BottomTabbedRenderer.FontSize = 10f;
            BottomTabbedRenderer.IconSize = 24;
            BottomTabbedRenderer.ItemTextColor = stateList;
            BottomTabbedRenderer.ItemIconTintList = stateList;
            //BottomTabbedRenderer.Typeface = Typeface.CreateFromAsset(this.Assets, "architep.ttf");
            //BottomTabbedRenderer.ItemBackgroundResource = Resource.Drawable.bnv_selector;
            BottomTabbedRenderer.ItemSpacing = 4;
            //BottomTabbedRenderer.ItemPadding = new Xamarin.Forms.Thickness(6);
            BottomTabbedRenderer.BottomBarHeight = 56;
            BottomTabbedRenderer.ItemAlign = ItemAlignFlags.Center;
            BottomTabbedRenderer.ShouldUpdateSelectedIcon = true;
            
            BottomTabbedRenderer.MenuItemIconSetter = (menuItem, iconSource, selected) => {
                var iconized = Iconize.FindIconForKey(iconSource.File);
                if (iconized == null)
                {
                    if (selected == true)
                        iconSource = iconSource + "_sel";
                    BottomTabbedRenderer.DefaultMenuItemIconSetter.Invoke(menuItem, iconSource, selected);
                    return;
                }
                var drawable = new IconDrawable(this, iconized).Color(selected ? Color.Red : Color.White).SizeDp(30);
                menuItem.SetIcon(drawable);

            };

        }

View Code

资源文件：

如此即可实现Android底部导航栏了。

在Xamarin.Forms 3.0中，由于Xamarin.Forms的一个bug，会导致页面在pop后导致崩溃，解决方案：http://www.cnblogs.com/devin_zhou/p/9028214.html