iOS独立存储Demo（调试过可以运行）

    NSArray *array1 = [NSArray arrayWithObjects:@"iphone",@"ipod",nil];
    NSArray *array2 = [NSArray arrayWithObjects:@"mac",@"imac",@"mac pro",nil];

    NSDictionary *myDictionary = [NSDictionary dictionaryWithObjectsAndKeys:array1,@"mobile",array2,@"computers",nil];
    
    
    
    NSString* path = NSHomeDirectory();
    
    NSFileManager *fileManager = [NSFileManager defaultManager];
   
    NSArray *directoryPath = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES);
    
    NSString *documentDirectory = [directoryPath objectAtIndex:0];
    
    NSString *filePath = [documentDirectory stringByAppendingPathComponent: @"aaaa"];
    if(![fileManager fileExistsAtPath: filePath])
    {
        [fileManager createFileAtPath: path contents: nil attributes:nil];
    }
    

    //write
    [myDictionary writeToFile: filePath atomically:YES];
 
    
    //read
    NSDictionary* read = [NSDictionary dictionaryWithContentsOfFile: filePath];