问如何在plist中保存值并访问plist？

EN

- (void)viewDidLoad {
    [super viewDidLoad];
    settings = [[NSMutableArray alloc]initWithObjects:@"Clock",@"Time Format",@"Weather",@"Degrees",nil];
    switchControl = [[UISwitch alloc]initWithFrame:CGRectMake(205, 110, 20, 15) ];
    [self.switchControl addTarget:self action:@selector(switchChanged:) forControlEvents:UIControlEventValueChanged];
    [self.view addSubview:switchControl];
    NSString *viewdid = @"ON";
    userdefaults = [NSUserDefaults standardUserDefaults];
    [userdefaults setObject:viewdid forKey:@"stateOfSwitch"];

}


- (void)viewWillAppear:(BOOL)animated {
    NSString    *_value= [[NSUserDefaults standardUserDefaults] stringForKey:@"stateOfSwitch"];

    if([_value compare:@"ON"] == NSOrderedSame){
        [switchControl setOn:YES animated:YES];
    }
    else {
        [switchControl setOn:NO animated:YES];
    }
    [super viewWillAppear:animated];
}



#pragma mark -
#pragma mark Table view data source

- (NSInteger)numberOfSectionsInTableView:(UITableView *)tableView {
    // Return the number of sections.
    return 1;
}


- (NSInteger)tableView:(UITableView *)tableView numberOfRowsInSection:(NSInteger)section {
    // Return the number of rows in the section.
    return 4;
}
-(void)switchChanged:(id)sender
{

    app= (StopSnoozeAppDelegate*)[[UIApplication sharedApplication]delegate];

        NSString *value = @"ON";
    userdefaults = [NSUserDefaults standardUserDefaults];
        if(!switchControl.on){
            value = @"OFF";
            [userdefaults setObject:value forKey:@"stateOfSwitch"];
        }
        [userdefaults setObject:value forKey:@"stateOfSwitch"];
    [userdefaults synchronize];

}


//this is my second class where i am accessing my userdefaults key and depending on that hiding the views
- (void) viewWillAppear:(BOOL)animated
{

    NSString *_value= [[NSUserDefaults standardUserDefaults] stringForKey:@"stateOfSwitch"];

    if([_value compare:@"ON"] == NSOrderedSame){
        newview.hidden = NO;
        newnewview.hidden =NO;
        firstview.hidden = NO;
        secondview.hidden = NO;
        thirdview.hidden = NO;



    }
    else if([_value compare:@"OFF"] == NSOrderedSame) {

        newview.hidden = YES;
        newnewview.hidden= YES;
        firstview.hidden = YES;
        secondview.hidden = YES;
        thirdview.hidden = YES;
    }

}