How to Change iphone Application Preferences Settings at run time?

Objective: I want to set iphone Application Preferences at run time

In Setting.Bundle I have title=Version and DefaultValue=1.0

So at run time if there is new version available i have to change iphone Application Preference Default Value. But i am not able to do so. It showing 1.0 instead of 1.1

I dont know whats wrong in my code

Code:

 NSString *settingsBundle = [[NSBundle mainBundle] pathForResource:@"Settings" ofType:@"bundle"];
if(!settingsBundle) {
    NSLog(@"Could not find Settings.bundle");
    return;
}

NSDictionary *settings = [NSDictionary dictionaryWithContentsOfFile:[settingsBundle stringByAppendingPathComponent:@"Root.plist"]];
NSArray *preferences = [settings objectForKey:@"PreferenceSpeci开发者_如何转开发fiers"];

NSMutableDictionary *defaultsToRegister = [[NSMutableDictionary alloc] initWithCapacity:[preferences count]];
for(NSDictionary *prefSpecification in preferences) {
    NSString *key = [prefSpecification objectForKey:@"Key"];
    if(key) {

        if([key isEqualToString:@"name_preference"])
        {
            NSString *a=[[NSBundle mainBundle] objectForInfoDictionaryKey:@"CFBundleVersion"];
            [defaultsToRegister setObject:a forKey:key];
        }
        else {
            [defaultsToRegister setObject:[prefSpecification objectForKey:@"DefaultValue"] forKey:key];

        }


    }
}

[[NSUserDefaults standardUserDefaults] registerDefaults:defaultsToRegister];

Your bundle is read-only, so anything you want to write needs to be externalized. You can use Standard Defaults to keep all that information if you want to. That is pretty straightforward:

NSString *version = [[NSBundle mainBundle] objectForInfoDictionaryKey:@"CFBundleShortVersionString"];
NSString *build = [[NSBundle mainBundle] objectForInfoDictionaryKey:@"CFBundleVersion"];
[standardDefaults setObject: build forKey:@"MyAppBuild"];
[standardDefaults setObject: version forKey:@"MyAppVersion"];
[standardDefaults synchronize]; 

Additionally, you can copy a plist to the device file system and read and write to/from that:

Reading:

+ (NSDictionary *) loadAppData {
    NSString *finalPath;

    // Load "defaults" plist
    NSArray *paths =  NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES); 
    NSString *documentsPath = [paths objectAtIndex:0]; 
    NSString *writablePath = [documentsPath stringByAppendingPathComponent:@"AppSettings.plist"];

    NSFileManager *fileManager = [NSFileManager defaultManager];
    if([fileManager fileExistsAtPath: writablePath]){
        finalPath = writablePath;
    }
    else{
        NSString *path = [[NSBundle mainBundle] bundlePath];
        finalPath = [path stringByAppendingPathComponent:@"AppSettings.plist"];
    }

    return [NSDictionary dictionaryWithContentsOfFile: finalPath];
}

Writing:

+ (void) saveAppData: (NSDictionary *) appData {

    // Load "defaults" plist
    NSArray *paths =  NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES); 
    NSString *documentsPath = [paths objectAtIndex:0]; 
    NSString *writablePath = [documentsPath stringByAppendingPathComponent:@"AppSettings.plist"];

    // Save it
    [appData writeToFile: writablePath atomically: YES];
}

I am having difficulty understanding the question, and your code is not easy to follow (I never use registerDefaults and the documentation on what it does is a little vague)

Bundles are read only. You cannot update bundles at runtime.

"So at run time if there is new version available i have to change iphone Application Preference Default Value." -- not really. The version value will be in the bundle already (taken from your app.plist)

I read the app version value from the bundle with the following line of code: NSString* version = [[[NSBundle mainBundle] infoDictionary] objectForKey:(NSString*)kCFBundleVersionKey];