如何确定首次在iphone上加载应用程序？

我希望第一次有人加载我的应用程序时，它会在我的首选项视图中启动，每隔一段时间就会在主视图中启动

我找不到一种方法来检测这是否是应用程序第一次运行。有什么想法吗

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

    // Override point for customization after application launch
    NSUserDefaults      *padFactoids;
    int                 launchCount;

    padFactoids = [NSUserDefaults standardUserDefaults];
    launchCount = [padFactoids integerForKey:@"launchCount" ] + 1;
    [padFactoids synchronize];

    NSLog(@"this is the number: %i of times this app has been launched", launchCount);
        if ( launchCount == 1 )
    {
        NSLog(@"this is the FIRST LAUNCH of the app");
        // do stuff here as you wish
        bbb = [[Blue alloc]init];
        [window addSubview:bbb.view];
    }
    if ( launchCount >= 2 )
    {
        NSLog(@"this is the SECOND launch of the damn app");
        // do stuff here as you wish
        rrr = [[Red alloc]init];
        [window addSubview:rrr.view];
    }
    [window makeKeyAndVisible];

    return YES;
}

在这两个类中，红色和蓝色都是uiviewcontroller的子类。唯一的区别是-（void）viewDidLoad{ self.view.backgroundcolor=[UIColor redColor]； }如果为红色，则为蓝色，背景色为蓝色

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但是，当我执行应用程序时，它只显示蓝色，不显示红色，这是我在运行应用程序时出错的地方。第二次，它显示红色。…

检查NSUserdefaults中的一些标志，如果没有，则显示首选项视图，并在设置这些设置后设置该标志

BOOL hasBeenStarted = [[NSUserDefaults standardUserDefaults] boolForKey:@"hasBeenStarted"];
if (!hasBeenStarted) {
    NSLog(@"Show panel");
    [[NSUserDefaults standardUserDefaults] setBool:YES forKey:@"hasBeenStarted"];
}

下面就是具体的操作方法。你会很高兴知道这是难以置信的简单。这正好是四行代码。

将此代码添加到任意位置。也许只是在应用程序中：在AppDelegate.m文件中的didfishlaunchingwithoptions:routine。或者，无论您在哪里为应用程序进行常规设置。（但是，请确保它只运行一次。）

除了最简单的应用程序外，几乎所有的应用程序都能做到这一点。希望能有帮助。从理论上讲，您不必为“synchronize”调用而烦恼，但我们发现，在大量实际用户运行中，如果您将其包括在内，则可能更可靠

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PS不要在首选项中使用布尔值。如果您是一名新程序员，则无法理解默认值，因此永远无法维护。坚持整数。（第一次不用时，它们总是一个“整数零”，所以你没有问题。）简单。希望有帮助。

如果在应用程序启动时创建一个

本地文件，效果会更好。并在每次启动时检查该文件是否存在

对于
NSUserDefault
，如果应用程序未在后台运行，则每次都会重新初始化

- (void)checkApplicationFirstLaunch
{
    if(![self getFileExistence:@"appinstall"])
    {
        // this is fresh install of the app
        [self createFileFromString:@"install" filename:@"appinstall"];
    }
    else
    {
        // app was already installed
    }
}

下面是我在上面使用的方法

- (BOOL) getFileExistence: (NSString *) filename
{
    BOOL IsFileExists = NO;

    NSArray *documentPaths = NSSearchPathForDirectoriesInDomains(NSCachesDirectory, NSUserDomainMask, YES);
    NSString *documentsDir = [documentPaths objectAtIndex:0];
    NSString *favsFilePath = [documentsDir stringByAppendingPathComponent:filename];

    NSFileManager *fileManager = [NSFileManager defaultManager];

    // Check if the database has already been created in the users filesystem
    if ([fileManager fileExistsAtPath:favsFilePath])
    {
        IsFileExists = YES;
    }
    return IsFileExists;
}

- (void)createFileFromString:(NSString *)string filename:(NSString *)filename
{
    NSArray *paths = NSSearchPathForDirectoriesInDomains(NSCachesDirectory, NSUserDomainMask, YES);
    NSString *documentsDirectory = [paths objectAtIndex:0]; // Get documents directory
    NSLog(@"%@", documentsDirectory);
    NSError *error;
    BOOL succeed = [string writeToFile:[documentsDirectory stringByAppendingPathComponent:filename] atomically:YES encoding:NSUTF8StringEncoding error:&error];
    if (!succeed){
        // Handle error here
        NSLog(@"Did not save: Error: %@", error);
    }
}

请详细解释
- (BOOL) getFileExistence: (NSString *) filename
{
    BOOL IsFileExists = NO;

    NSArray *documentPaths = NSSearchPathForDirectoriesInDomains(NSCachesDirectory, NSUserDomainMask, YES);
    NSString *documentsDir = [documentPaths objectAtIndex:0];
    NSString *favsFilePath = [documentsDir stringByAppendingPathComponent:filename];

    NSFileManager *fileManager = [NSFileManager defaultManager];

    // Check if the database has already been created in the users filesystem
    if ([fileManager fileExistsAtPath:favsFilePath])
    {
        IsFileExists = YES;
    }
    return IsFileExists;
}

- (void)createFileFromString:(NSString *)string filename:(NSString *)filename
{
    NSArray *paths = NSSearchPathForDirectoriesInDomains(NSCachesDirectory, NSUserDomainMask, YES);
    NSString *documentsDirectory = [paths objectAtIndex:0]; // Get documents directory
    NSLog(@"%@", documentsDirectory);
    NSError *error;
    BOOL succeed = [string writeToFile:[documentsDirectory stringByAppendingPathComponent:filename] atomically:YES encoding:NSUTF8StringEncoding error:&error];
    if (!succeed){
        // Handle error here
        NSLog(@"Did not save: Error: %@", error);
    }
}

BOOL hasBeenStarted = [[NSUserDefaults standardUserDefaults] boolForKey:@"hasBeenStarted"];
if (!hasBeenStarted) {
    NSLog(@"Show panel");
    [[NSUserDefaults standardUserDefaults] setBool:YES forKey:@"hasBeenStarted"];
    [[NSUserDefaults standardUserDefaults]synchronize];// save to NSUserDefaults

}