Basic Setup of iCloud and Key-Value Storage - Beginning iOS Cloud and Database Development - page 46

-(void)updateDefaultForTextField:(UITextField *)textField {
NSUserDefaults *userDefaults = [NSUserDefaults standardUserDefaults];
if([textField isEqual:_txtDisplayName]){
if(![[userDefaults stringForKey:CTDisplayName] isEqualToString:textField.text]){
[userDefaults setObject:textField.text forKey:CTDisplayName];
[userDefaults synchronize];
}
} else {
if(![[userDefaults stringForKey:CTFavoriteNumber] isEqualToString:textField.text]){
[userDefaults setObject:[NSNumber numberWithFloat:[textField.text floatValue]]
forKey:CTFavoriteNumber];
[userDefaults synchronize];
}
}
}
We start off by grabbing the reference to our NSUserDefaults object. We then add an if statement to
check whether we are working with _txtDisplayName textfield or _txtFavoriteNumber . We use this to
determine which key we should be working with. Then we check the current text field value against
the userDefaults value to determine whether a change has in fact been made. If a change was
made, we set the new value in userDefaults and call synchronize . The synchronize method is what
forces the save to take place in NSUserDefaults ; otherwise the OS invokes this method automatically
at periodic intervals.
Next we adopt the UITextFieldDelegate protocol. Adopting this protocol tells the compiler that
we intend to act as the delegate for a UITextField and that we will implement all required delegate
methods as well as any optional methods. If your class does not completely conform to the protocol,
the compiler will give you warnings letting you know. Select the SettingsViewController.h file and
change the interface definition to this:
@interface SettingsViewController : UITableViewController <UITextFieldDelegate>
In the SettingsViewController.m file we need to add one optional UITextFieldDelegate method.
The method we implement is textFieldShouldReturn: . This method is called when the user presses
Return on the keyboard. We use this method to change the first responder. In our case the first
responder is the object that will be responding to the keyboard. We will also add a pragma mark
above this method so that we can easily find it in the jump bar.
#pragma mark - UITextFieldDelegate Methods
- (BOOL)textFieldShouldReturn:(UITextField *)textField {
[self updateDefaultForTextField:textField];
if([textField isEqual:_txtDisplayName])
[_txtFavoriteNumber becomeFirstResponder];
else
[_txtFavoriteNumber resignFirstResponder];
return YES;
}