The simplest way to save user preference/data on iPhone is using NSUserDefaults. Here comes another easy way to save data in filesystem.
In this example, we are going to create an array, fill it with values and then save the contents of the array to the documents directory of our app.
Then, after stopping the program and putting in code, we will retrieve the array from the filesystem. Finally, to prove that it all worked we will use an alert box to inform the user of what is in the array that we stored.
First, in the applicationDidFinishLaunching method put in this code:
//get the documents directory:
NSArray *paths = NSSearchPathForDirectoriesInDomains
(NSDocumentDirectory, NSUserDomainMask, YES);
NSString *documentsDirectory = [paths objectAtIndex:0];
//make a file name to write the data to using the
//documents directory:
NSString *fullFileName = [NSString stringWithFormat:@"%@/newFileArray", documentsDirectory];
//create an array and add values to it:
NSMutableArray *array = [[NSMutableArray alloc] init];
[array addObject:@"First string"];
[array addObject:@"Second string"];
[array addObject:@"Third string"];
//this statement is what actually writes out the array
//to the file system:
[array writeToFile:fullFileName atomically:NO];
Now, your information has been saved to the iPhone’s file system in the documents directory of your app. Here is how you would retrieve the information that you saved:
//get the documents directory:
NSArray *paths = NSSearchPathForDirectoriesInDomains
(NSDocumentDirectory, NSUserDomainMask, YES);
NSString *documentsDirectory = [paths objectAtIndex:0];
//make a file name to write the data to using the
//documents directory:
NSString *fullFileName = [NSString stringWithFormat:@"%@/newFileArray", documentsDirectory];
//retrieve your array by using initWithContentsOfFile while passing
//the name of the file where you saved the array contents.
NSMutableArray *array = [[NSMutableArray alloc] initWithContentsOfFile:fullFileName];
NSLog(@"%@", array);
That's it – a quick and easy way to save information on the iPhone. The array is easily saved and retrieved from iPhone filesystem.
