从feed获取充填UIPickerView

解析一个feed到NSMutableArray，填充UIPickerView如下：

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

- (NSInteger)pickerView:(UIPickerView *)thePickerView numberOfRowsInComponent:(NSInteger)component {
return [items count];
}

- (NSString *)pickerView:(UIPickerView *)thePickerView titleForRow:(NSInteger)row     forComponent:(NSInteger)component {
return [items objectAtIndex:row];
}

-(void)pickerView:(UIPickerView *)pickerView didSelectRow:(NSInteger)row
  inComponent:(NSInteger)component
{
id item = [items objectAtIndex:row];
NSString *occasion = [item objectForKey:@"name"];
location.text = occasion;
}

但是运行之后，UIPickerView没有任何值，