自定义TabBar-IOS学习

　　UITabBarController是在IOS应用开发中很常用的一个类，继承于UIViewController，来实现多个视图间的切换，但很多时候系统自带的TabBar不能满足我们的需求，系统自带的一些属性我们往往无法修改，像切换项的图片的大小，这时候就需要我们自定义TabBar。例如，我们想实现下方的TabBar的这个效果，使用系统的就无法完成。

演示所需图片下载地址http://download.csdn.net/detail/zsmile123/8136531

------------------------------------------------------下面演示过程-----------------------------------------------

首先，新建一个继承于UIViewController得视图控制器，随便起名为CustomTarBarViewController，勾选上xib。我们首先来布局一下TabBar，也就是模仿系统的TabBar

-----------------------------依次拖放view，imageView，以及5个button，并给5个button设置tag值为1，2，3，4，5------------------------------------------------

----------------------------------------------------------------------------------------------------

 ----------------------------------------CustomTarBarViewController.h文件中--------------------------------------------

#import <UIKit/UIKit.h>

@interface CustomTarBarViewController : UIViewController<UINavigationControllerDelegate>

{

    //正常状态下的图片数组

    NSArray *_nomalImageArray;

    //高亮状态下的图片数组

    NSArray *_hightlightedImageArray;

}

//添加两个属性，selectedIndex用来记录选中的是那一个视图（或button），viewControllers数组用来存放button点击对应的视图控制器

@property (nonatomic ,assign)NSInteger selectedIndex;

@property (nonatomic ,retain)NSArray *viewControllers;

//将xib中的view，和5个button连线

@property (retain, nonatomic) IBOutlet UIView *tabBarView;　　　　

- (IBAction)tabBarButtonClick:(UIButton *)sender;

@end

-----------------------------------------------------------CustomTarBarViewController.m文件中------------------------------------

- (id)initWithNibName:(NSString *)nibNameOrNil bundle:(NSBundle *)nibBundleOrNil

{

    self = [super initWithNibName:nibNameOrNil bundle:nibBundleOrNil];

    if (self) {

　　//这里是为了每次首次进入都能加载第一个视图

        _selectedIndex = -1;

        }

    return self;

}

- (void)viewDidLoad

{

    [super viewDidLoad];

    self.view.backgroundColor = [UIColor redColor];  

    //正常状态下按钮图片

    _nomalImageArray = [[NSArray alloc] initWithObjects:@"tabbar_button_binders_normal.png",@"tabbar_button_updates_normal.png",@"tabbar_button_centeradd.png",@"tabbar_button_sessions_normal.png",@"tabbar_button_notes_normal.png",nil];

　　//高亮状态下按钮图片

　　_hightlightedImageArray = [[NSArray alloc]initWithObjects:@"tabbar_button_binders_selected.png",@"tabbar_button_updates_selected.png",@"tabbar_button_centeradd.png",@"tabbar_button_sessions_selected.png",@"tabbar_button_notes_selected.png",nil];

    if (_selectedIndex == -1)

    {

        self.selectedIndex = 0 ;

    }

 }

#pragma mark ----切换视图选项

- (IBAction)tabBarButtonClick:(UIButton *)sender

{

    //当前选中的button  self.selectedIndex会调用set方法，button的tag值-1即为其对应的视图

    self.selectedIndex = sender.tag - 1;

}

#pragma mark ----重写selectedIndex属性的set方法

- (void)setSelectedIndex:(NSInteger)aselectedIndex

{

    //判断新的值与原来的值是否相等，相等则选择的任然是当前视图，不做处理

    if (aselectedIndex == _selectedIndex)

    {

        return;

    }

    //_selectedIndex >=0说明选中了某一按钮

    if (_selectedIndex >= 0)

    {

        //需要将前一个视图移除

        //根据_selectedIndex从视图控制器数组中取出先前选中的视图

        UIViewController *previousViewController = [_viewControllers objectAtIndex:_selectedIndex ];

        [previousViewController.view removeFromSuperview];

        //需要将前一个button的图片改为普通状态的图片

        UIButton *previousButton = (UIButton *)[self.view viewWithTag:_selectedIndex+1];

        [previousButton setBackgroundImage:[UIImage imageNamed:[_nomalImageArray objectAtIndex:_selectedIndex]] forState:(UIControlStateNormal)];

    }

    //然后将新的aselectedIndex赋值给_selectedIndex

    _selectedIndex = aselectedIndex;

    //显示新的视图

    UIViewController *currentViewController = [_viewControllers objectAtIndex:_selectedIndex];

    //找到当前button，将其背景图片改为高亮

    UIButton *currentButton = (UIButton *)[self.view viewWithTag:_selectedIndex + 1];

    [currentButton setBackgroundImage:[UIImage imageNamed:[_hightlightedImageArray objectAtIndex:_selectedIndex]] forState:(UIControlStateNormal)];

    //由于第一个视图是加在导航中的，所以需要判断

    if ([currentViewController isKindOfClass:[UINavigationController class]])

    {

        //表示这个视图是navgationController

        //设置导航的代理

        ((UINavigationController *)currentViewController).delegate = self;

    }

    //设置当前视图的大小

    currentViewController.view.frame = CGRectMake(0, 0, 320, self.view.bounds.size.height-44);

    //添加到tab的view上

    [self.view addSubview:currentViewController.view];

    [self.view sendSubviewToBack:currentViewController.view];

}

@end

--------------------------------------AppDelegate.h文件中给TabBar添加视图------------------------------------------------

#import "AppDelegate.h"

#import "CustomTarBarViewController.h"

 @implementation AppDelegate

 - (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions

{

    self.window = [[UIWindow alloc] initWithFrame:[[UIScreen mainScreen] bounds]];

    self.window.backgroundColor = [UIColor whiteColor];

    [self.window makeKeyAndVisible];

    //这里给第一个视图添加了导航，也可不添加（这里演示导航的添加）

    UIViewController *homeVC = [[UIViewController alloc] init] ;

　 homeVC.view.backgroundColor = [UIColor redColor];

    UINavigationController *nav = [[[UINavigationController alloc] initWithRootViewController:homeVC] autorelease];

    UIViewController *setVC = [[UIViewController alloc] init] ;

　 setVC.view.backgroundColor = [UIColor blueColor];

    UIViewController *shareVC = [[UIViewController alloc] init] ;

　 shareVC.view.backgroundColor = [UIColor yellowColor];

    UIViewController *plusVC = [[UIViewController alloc] init] ;

　 plusVC.view.backgroundColor = [UIColor greenColor];

    UIViewController *playVC = [[UIViewController alloc] init];

　 playVC.view.backgroundColor = [UIColor orangeColor];

    CustomTarBarViewController *tabVC = [[CustomTarBarViewController alloc] init] ;

　　//将视图加到tabVC中

    tabVC.viewControllers = [NSArray arrayWithObjects:nav,setVC,shareVC,plusVC,playVC, nil];

    self.window.rootViewController = tabVC;

    return YES;

}