ios 文件操作

1.每个ios程序都有一个这样的目录：

2.获取Documents目录：

    NSArray *path=NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES);
    NSString *documentsDirectory=[path objectAtIndex:0];
    NSLog(@"%@",documentsDirectory);

在末尾附加另一个字符串来创建文件名

NSString *fname=[documentsDirectory stringByAppendingPathComponent:@"newFile.txt"];//完整路径

3.获取tmp目录:

NSString *temPath=NSTemporaryDirectory();

4. 把2个textField的数据保存，下次打开时加载。

-(NSString *)dataFilePath//返回文件路径
{
    NSString *fileName=@"userdata.txt";
    NSArray *path=NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES);
    NSString *documentDirectory=[path objectAtIndex:0];
    return [documentDirectory stringByAppendingPathComponent:fileName];
}

文件操作

-(IBAction)saveToFile
{
    NSMutableArray *array=[[NSMutableArray alloc] init];
    [array addObject:text1.text];
    [array addObject:text2.text];
    [array writeToFile:[self dataFilePath] atomically:YES];
}

-(IBAction)loadFromFile
{
    NSString *filePath=[self dataFilePath];
    if ([[NSFileManager defaultManager] fileExistsAtPath:filePath])
    {
        NSArray *array=[[NSArray alloc] initWithContentsOfFile:filePath];
        text1.text=[array objectAtIndex:0];
        text2.text=[array objectAtIndex:1];
    }
    UIApplication *app=[UIApplication sharedApplication];//为关闭做准备
    [[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(applicationWillResignActive:) name:UIApplicationWillResignActiveNotification object:app];
}

程序打开时读取，程序退到后台时写入

- (void)viewDidLoad
{
    [super viewDidLoad];
    
    [self loadFromFile];
}

-(void) applicationWillResignActive:(NSNotification *)notification //在viewController中
{
    [self saveToFile];
}