Picker saves random data to NSUserDefaults - ios

Question

I've been working on a new tips & tricks project for a game called Dofus. In the first view the user is asked to pick their class out of a picker. Then they go to a next view and pick their level and stuff like that. The problem with the picker however is that its getting the wrong class out of the picker.
- (NSInteger)numberOfComponentsInPickerView:(UIPickerView *)pickerView {
return 1;
}
- (NSInteger)pickerView:(UIPickerView *)pickerView numberOfRowsInComponent:(NSInteger)component {
return [self.classNames count];
}
- (NSString *)pickerView:(UIPickerView *)pickerView
titleForRow:(NSInteger)row
forComponent:(NSInteger)component {
NSUserDefaults *prefs = [NSUserDefaults standardUserDefaults];
NSString *_myClass = self.classNames[row];
[prefs setObject:_myClass forKey:#"class"];
return self.classNames[row];
}
In the ViewDidLoad i declared my classes:
- (void)viewDidLoad {
[super viewDidLoad];
// Do any additional setup after loading the view, typically from a nib.
self.view.backgroundColor = [UIColor colorWithPatternImage:[UIImage imageNamed:#"background"]];
self.classNames = #[#"Cra", #"Ecaflip", #"Eliotrope", #"Eniripsa",
#"Enutrof", #"Feca", #"Foggernout", #"Iop", #"Masqueraider", #"Osamodas", #"Pandawa", #"Rogue", #"Sacrier", #"Sadida", #"Sram", #"Xelor"];
}
Then in the next view I get the information like this (different .m file):
- (void)viewDidLoad {
[super viewDidLoad];
// Do view setup here.
self.view.backgroundColor = [UIColor colorWithPatternImage:[UIImage imageNamed:#"background"]];
NSUserDefaults *prefs = [NSUserDefaults standardUserDefaults];
// getting an NSString
NSString *myClass = [prefs stringForKey:#"class"];
_textLabel.text = [NSString stringWithFormat:#"So you are a %# huh? Pretty cool! Its a good class. Fill out the rest so we are ready to go!", myClass];
}
Anyone any idea's how this is happening? Thanks in advance!

Answer 1

You are setting your preferences on the Picker's datasource call for the row title, instead of the delegate call for when the row is selected. For every row that is loaded into the view, pickerView:titleForRow:forComponent: is called, at which point you set the class preference, however, this does not correspond to the row that is selected in the picker, it corresponds to the next row to be displayed.
Instead, respond to the
pickerView:didSelectRow:inComponent: method, and set your preference there (you will still need to respond to the other one to set the row titles, just don't set the preference).
- (NSString *)pickerView:(UIPickerView *)pickerView
didSelectRow:(NSInteger) row
inComponent:(NSInteger) component {
NSUserDefaults *prefs = [NSUserDefaults standardUserDefaults];
NSString *_myClass = self.classNames[row];
[prefs setObject:_myClass forKey:#"class"];
}

Answer 2

If you want store the selected row by the user you should this method from UIPickerViewDelegate
- (void)pickerView:(UIPickerView *)pickerView didSelectRow:(NSInteger)row inComponent:(NSInteger)component;
Something like that would work:
- (void)pickerView:(UIPickerView *)pickerView didSelectRow:(NSInteger)row inComponent:(NSInteger)component
{
NSUserDefaults *prefs = [NSUserDefaults standardUserDefaults];
NSString *_myClass = self.classNames[row];
[prefs setObject:_myClass forKey:#"class"];
[prefs synchronize];
}
}
Take a look at these links to better understand how works UIPickerView :
http://nscookbook.com/2013/01/ios-programming-recipe-7-using-the-uipickerview/
http://www.techotopia.com/index.php/An_iOS_7_UIPickerView_Example
https://developer.apple.com/library/ios/documentation/UIKit/Reference/UIPickerView_Class/index.html#//apple_ref/doc/uid/TP40006842-CH3-SW9