How would I save and load a UITextField?

问题:

I have searched everywhere and tried lots of code but nothing seems to be working for me. All I need to do is to load (on viewDidLoad) a text field and save it when a button is pressed.

What is the easiest method of doing this? I am working with a single window application, I don't have a view controller (this may make a difference?)

Thanks,

James

回答1:

Using an SQLite database:

-(IBAction) checkNotes{

sqlite3_stmt *statement;

const char *dbpath = [databasePath UTF8String];

if (sqlite3_open(dbpath, &contactDB) == SQLITE_OK)
{
    NSString *querySQL = [NSString stringWithFormat: @"SELECT Notes FROM NotesTable WHERE UserID = (\"%@\")", userID.text]; 

    const char *query_stmt = [querySQL UTF8String];

    sqlite3_prepare_v2(contactDB, query_stmt, -1, &statement, NULL);

    if (sqlite3_step(statement) == SQLITE_ROW) {

        NSString *notesField = [[NSString alloc] initWithUTF8String:(const char *) sqlite3_column_text(statement, 0)];

        Notes.text = notesField;

        [notesField release];

    }else{
        Status.text = @"Not found";

    }

    sqlite3_finalize(statement);
}
sqlite3_close(contactDB);    

}

You can play around a little bit and adapt this code to your needs. For implementing SQLite3, check the net. But it will help you much in the future I guess. I think it would be the most flexible, because it will also allow you to create relational databases.

回答2:

Create a NSMutableDictionary as property and ...

when your button is clicked:

-(IBAction)buttonClicked:(id)sender
{
NSArray *paths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES);
NSString *documentsDirectory = [paths objectAtIndex:0];   
NSString *devicePath = [documentsDirectory stringByAppendingPathComponent:@"yourfile.txt"]; 
[self.dictionary setObject:self.textField.Text key:@"textField"];
[self.dictionary writeToFile:devicePath atomically:YES];
}

On your viewDidLoad, you can get the value of the file by:

NSString *filePath = [[NSBundle mainBundle] pathForResource:@"youefile"
                                                     ofType:@"txt"];
self.dictioary = [[[NSMutableDictionary alloc] initWithContentsOfFile:filePath] autorelease];

回答3:

Use the NSUserDefaults class which was specifically made for this scenario.

NSUserDefaults *defs = [NSUserDefaults standardUserDefaults];

// saving a NSString (you usually do this when the value is being submitted)
[defs setObject:textField.text forKey:@"aKey"];
[defs synchronize]; //this commits the new value - shouldn't be necessary because this is doe automatically, but just in case...

// loading a NSString (you usually do this on viewDidLoad)
testField.text = [defs objectForKey:@"aKey"];

The value is stored across sessions.
You can store other value types as well (other than NSString).
Use a different key for each field for which you want to store values.
This can also be used to store app configurations/options/etc