RTY 实践出真知

功能创建一个test.plist文件，textInput作为输入，displayLabel作为显示，有一个按钮来触发保持程序triggerStorage；

-(void)triggerStorage
{
    displayLabel.text = textInput.text;
    
    NSArray *paths=NSSearchPathForDirectoriesInDomains(NSDocumentDirectory,NSUserDomainMask,YES);
    NSString *path=[paths    objectAtIndex:0];  
    NSString *filename=[path stringByAppendingPathComponent:@"test.plist"];   //获取路径
    
    NSDictionary* dic2 = [NSDictionary dictionaryWithContentsOfFile:filename];  //读取数据
    NSLog(@"dic2 is:%@",dic2); 
    
    //创建一个dic，写到plist文件里
    NSDictionary* dic = [NSDictionary dictionaryWithObjectsAndKeys:displayLabel.text,@"IP",nil]; //写入数据
    [dic writeToFile:filename atomically:YES];   

}

// Implement viewDidLoad to do additional setup after loading the view, typically from a nib.
- (void)viewDidLoad
{
    NSMutableArray *resultData; 
    NSArray *paths=NSSearchPathForDirectoriesInDomains(NSDocumentDirectory,NSUserDomainMask,YES);
    NSString *path=[paths objectAtIndex:0];
    NSLog(@"path = %@",path);   
    NSString *filename=[path stringByAppendingPathComponent:@"test.plist"]; 
  
    //读文件
    NSDictionary* dic2 = [NSDictionary dictionaryWithContentsOfFile:filename];
    NSLog(@"dic is:%@",dic2);    
    if(dic2 == nil)
    {
        //1. 创建一个plist文件 
        NSFileManager* fm = [NSFileManager defaultManager];
        [fm createFileAtPath:filename contents:nil attributes:nil];        
    }
    else
    {
        resultData=[dic2 objectForKey:@"IP"]; 
        if([dic2 count] > 0)
        {
            displayLabel.text = resultData;
        }
        else
        {
            displayLabel.text = @" ";
        }
    }
    self.navigationItem.rightBarButtonItem = [[[UIBarButtonItem alloc]   //按钮的初始化及触发条件设置
                                               initWithTitle:@"保存" 
                                               style:UIBarButtonItemStylePlain 
                                               target:self 
                                               action:@selector(triggerStorage)] autorelease];    
    [super viewDidLoad];
}

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参考代码：

    NSLog(@"dic is:%@",dic2);