how to write content in text file in objective C i

问题:

I am writing content in iPhone. I used this code

NSArray *paths = NSSearchPathForDirectoriesInDomains( NSDocumentDirectory, NSUserDomainMask, YES);
NSString *filePath = [[paths objectAtIndex:0]stringByAppendingPathComponent:@"data.txt"];
NSString *temp = [[NSString alloc] initWithString:@"my name is gaurav"];
[temp writeToFile:filePath atomically:YES encoding:NSUTF8StringEncoding error:nil];
[temp release];

While I am trying to over write this file with new content with this code

NSArray *paths = NSSearchPathForDirectoriesInDomains( NSDocumentDirectory, NSUserDomainMask, YES);
NSString *filePath = [[paths objectAtIndex:0]stringByAppendingPathComponent:@"data.txt"];
NSString *matter = [[NSString alloc] initWithString:@"Hello iPhone"];

[matter writeToFile:filePath atomically:YES encoding:NSUTF8StringEncoding error:nil];
[matter release];

If I passed YES in atomically then file is not overwritten. and If I placed No there then file will overwrite but program is also halted and exit.

[matter writeToFile:filePath atomically:YES encoding:NSUTF8StringEncoding error:nil];

回答1:

I have tried. it is working. you just create test project. and write following code in viewDidLod method. and see text file content from document directory. it will get overwrite.

- (void)viewDidLoad
{
    [super viewDidLoad];
    // Do any additional setup after loading the view, typically from a nib.

    NSArray *paths = NSSearchPathForDirectoriesInDomains( NSDocumentDirectory, NSUserDomainMask, YES);
    NSString *filePath = [[paths objectAtIndex:0]stringByAppendingPathComponent:@"data.txt"];
    NSString *temp = [[NSString alloc] initWithString:@"my name is gaurav"];
    [temp writeToFile:filePath atomically:YES encoding:NSUTF8StringEncoding error:nil];
    [temp release];

    NSString *matter = [[NSString alloc] initWithString:@"Hello iPhone"];
    [matter writeToFile:filePath atomically:NO encoding:NSUTF8StringEncoding error:nil];
    [matter release];

}