根據應用程序首選項加載不同的初始視圖？

Question

我有一個首選項，設置時強制我的應用程序在啓動時執行一些同步。

我可以使用IB根據此設置顯示不同的初始視圖嗎？

有沒有一個標準的方法來實現這種行爲？

Answer 1

假設你有那是你的同步過程中設置，在初始視圖控制器initWithNibNamed您的應用程序委託一個屬性：方法檢查由應用程序代理同步的值，並加載適當筆尖通過調用[super initWithNibNamed:@"thisNibInsteadOfThatNib"];

編輯：顯示代碼以啓動取決於一些條件，在發射

// AppDelegate.h 
#import <UIKit/UIKit.h> 

@interface AppDelegate : NSObject <UIApplicationDelegate> 
{ 
    UIWindow *window; 
    UIViewController *firstViewController; 
} 
@property {nonatomic, retain} UIWindow *window; 
@end 

// AppDelegate.m 
#import AppDelegate.h 
#import ViewControllerOne.h 
#import ViewControllerTwo.h 

- (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions 
{ 
    BOOL shouldLoadViewOne = \\ some value from preferences 

    if (shouldLoadViewOne) { 
     firstViewController = [[ViewOneController alloc] initWithNibName:@"ViewOneController" bundle:nil]; 
    } else { 
     firstViewController = [[ViewTwoController alloc] initWithNibName:@"ViewTwoController" bundle:nil]; 
    } 

    UINavigationController *navController = [[UINavigationController alloc] initWithRootViewController:firstViewController]; 

    [window addSubView:[navController view]]; 

    [window makeKeyAndVisible]; 

    return YES; 
} 

EDIT 2的不同視圖：

使用NSClassFromSting()並保存要在首選項中加載的firstViewController的名稱。

// AppDelegate.h 
#import <UIKit/UIKit.h> 

@interface AppDelegate : NSObject <UIApplicationDelegate> 
{ 
    UIWindow *window; 
    id firstViewController; 
} 
@property {nonatomic, retain} UIWindow *window; 

- (NSString *)firstViewControllerName; 

@end 

// AppDelegate.m 
#import AppDelegate.h 
#import ViewControllerOne.h 
#import ViewControllerTwo.h 

- (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions 
{ 
    NSString *viewControllerName = [self firstViewControllerName]; 

    firstViewController = [[NSClassFromString(viewControllerName) alloc] initWithNibName:viewControllerName bundle:nil]; 

    UINavigationController *navController = [[UINavigationController alloc] initWithRootViewController:firstViewController]; 

    [window addSubView:[navController view]]; 

    [window makeKeyAndVisible]; 

    return YES; 
} 

- (NSString *)firstViewControllerName 
{ 
    NSString *defaultViewController = @"ViewOneController"; 
    NSString *savedFirstViewController = // string retrieved from preferences or other persistent store 

    if (!savedFirstViewController) 
     return defaultViewController; 

    return savedFirstViewController; 
}