cómo administrar este selector ver una fuente de datos

Question

Aquí estoy añadiendo un pickerview programaticly

- (void)viewDidLoad { 
     [super viewDidLoad]; 
     CGRect pickerFrame = CGRectMake(0,280,321,200); 

     UIPickerView *myPickerView = [[UIPickerView alloc] init]; //Not sure if this is the proper allocation/initialization procedure 

     //Set up the picker view as you need it 

     //Set up the display frame 
     myPickerView.frame = pickerFrame; //I recommend using IB just to get the proper width/height dimensions 

     //Add the picker to the view 
     [self.view addSubview:myPickerView]; 
    } 

Pero ahora tengo que realmente haga que sea mostrar contenidos y de alguna manera saber cuando se cambia y qué valor se ha cambiado a. ¿Cómo hago esto?

Answer 1

en lugar de archivos .h este código

@interface RootVC : UIViewController <UIPickerViewDelegate, UIPickerViewDataSource> 

asignar el origen de datos y delegar en el selector de

// this view controller is the data source and delegate 
myPickerView.delegate = self; 
myPickerView.dataSource = self; 

utilizan los siguientes métodos delegado y datasouce

- (void)pickerView:(UIPickerView *)pickerView didSelectRow:(NSInteger)row inComponent:(NSInteger)component 
{ 

} 

- (CGFloat)pickerView:(UIPickerView *)pickerView widthForComponent:(NSInteger)component 
{ 
    return 200; 
} 

- (CGFloat)pickerView:(UIPickerView *)pickerView rowHeightForComponent:(NSInteger)component 
{ 
    return 50; 
} 

- (NSString *)pickerView:(UIPickerView *)pickerView titleForRow:(NSInteger)row forComponent:(NSInteger)component 
{ 
    NSString *returnStr = @""; 
    if (pickerView == myPickerView) 
    {  
     returnStr = [[levelPickerViewArray objectAtIndex:row] objectForKey:@"nodeContent"]; 
    } 

    return returnStr; 
} 

- (NSInteger)pickerView:(UIPickerView *)pickerView numberOfRowsInComponent:(NSInteger)component 
{ 
    if (pickerView == myPickerView) 
    { 
     return [levelPickerViewArray count]; 
    } 
} 

- (NSInteger)numberOfComponentsInPickerView:(UIPickerView *)pickerView 
{ 
    return 1; 
} 

Answer 2

Debe crear una clase que implemente el protocolo UIPickerViewDataSource y asignarle una instancia a myPickerView.dataSource.