typedef NS_ENUM(NSInteger, UIBarStyle) {
  UIBarStyleDefault     = 0,    //默认风格，蓝色文字
  UIBarStyleBlack      = 1,    //黑色背景，褐色文字
  UIBarStyleBlackOpaque   = 1,  // 纯黑色背景,白色文字
  UIBarStyleBlackTranslucent = 2,  // 透明黑色背景,白色文字
};

@property(nonatomic)    UIBarStyle barStyle;  //工具栏风格，默认为蓝色
@property(nonatomic,copy)  NSArray  *items;   //工具栏中的按钮单元,UIBarButtonItem
@property(nonatomic,assign,getter=isTranslucent) BOOL translucent //是否透明
@property(nonatomic,retain) UIColor *tintColor;    //按钮颜色
@property(nonatomic,retain) UIColor *barTintColor； //工具栏颜色

- (void)setItems:(NSArray *)items animated:(BOOL)animated; 

#import <UIKit/UIKit.h>
@class RootViewController;
@interface AppDelegate : UIResponder <UIApplicationDelegate>
@property (strong, nonatomic) UIWindow *window;
@property (strong, nonatomic) RootViewController *rootViewController;
@end

- (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions
{
  self.window = [[UIWindow alloc] initWithFrame:[[UIScreen mainScreen] bounds]];
  // Override point for customization after application launch.
  self.rootViewController = [[RootViewController alloc] initWithNibName:@"RootView" bundle:nil]; 
  UIView *rootView = self.rootViewController.view; 
  CGRect rootViewFrame = rootView.frame; 
  rootViewFrame.origin.y += [UIApplication sharedApplication].statusBarFrame.size.height; 
  rootView.frame = rootViewFrame; 
  [self.window addSubview:rootView]; 
  self.window.backgroundColor = [UIColor whiteColor];
  [self.window makeKeyAndVisible];
  return YES;
}

#import <UIKit/UIKit.h>
@class FirstViewController;
@class SecondViewController;
@interface RootViewController : UIViewController
@property (strong, nonatomic) FirstViewController *firstViewController;
@property (strong, nonatomic) SecondViewController *secondViewController;
- (IBAction)switchViews:(id)sender;
@end

#import "FirstViewController.h"
#import "SecondViewController.h"

@synthesize firstViewController;
@synthesize secondViewController;

- (void)viewDidLoad
{
  self.firstViewController = [[FirstViewController alloc] initWithNibName:@"FirstView" bundle:nil];
  [self.view insertSubview: firstViewController.view atIndex:0];
  [super viewDidLoad];
}

- (IBAction)switchViews:(id)sender {
  if (self.secondViewController.view.superview == nil) {
    if (self.secondViewController == nil) { 
      self.secondViewController = [[SecondViewController alloc] initWithNibName:@"SecondView" bundle:nil]; 
    } 
    [firstViewController.view removeFromSuperview]; 
    [self.view insertSubview:self.secondViewController.view atIndex:0]; 
  } else {
    if (self.firstViewController == nil) { 
      self.firstViewController = 
      [[FirstViewController alloc] initWithNibName:@"FirstView" bundle:nil]; 
    } 
    [secondViewController.view removeFromSuperview]; 
    [self.view insertSubview:self.firstViewController.view atIndex:0]; 
  } 
}

- (void)didReceiveMemoryWarning
{
  [super didReceiveMemoryWarning];
  if (self.firstViewController.view.superview == nil) { 
    self.firstViewController = nil; 
  } else { 
    self.secondViewController = nil; 
  } 
}

- (IBAction)switchViews:(id)sender { 
  [UIView beginAnimations:@"View Flip" context:nil]; 
  [UIView setAnimationDuration:1.25]; 
  [UIView setAnimationCurve:UIViewAnimationCurveEaseInOut];
  if (self.secondViewController.view.superview == nil) { 
    if (self.secondViewController == nil) { 
      self.secondViewController = [[SecondViewController alloc] initWithNibName:@"SecondView" bundle:nil]; 
    } 
    [UIView setAnimationTransition: UIViewAnimationTransitionFlipFromRight forView:self.view cache:YES]; 
    [self.firstViewController.view removeFromSuperview]; 
    [self.view insertSubview:self.secondViewController.view atIndex:0]; 
  } else { 
    if (self.firstViewController == nil) { 
      self.firstViewController = [[FirstViewController alloc] initWithNibName:@"FirstView" bundle:nil]; 
    } 
    [UIView setAnimationTransition: UIViewAnimationTransitionCurlUp forView:self.view cache:YES]; 
    [self.secondViewController.view removeFromSuperview]; 
    [self.view insertSubview:self.firstViewController.view atIndex:0]; 
  } 
  [UIView commitAnimations]; 
}

UIViewAnimationTransitionFlipFromLeft
UIViewAnimationTransitionFlipFromRight
UIViewAnimationTransitionCurlDown
UIViewAnimationTransitionCurlUp