ios - viewDidAppear 时如何调用 pickerview 的委托(delegate)？

Question

我需要在我的 pickerview 中最后选择的行在 View 出现时被完全召回!我的 viewDidAppear 中有这段代码，它动画到最后选定的行，但它并没有真正调用我行中的 delegate 和 NSLog如果不触摸我的选择器并重新选择它们，将无法打印。

我该怎么做？

- (void)viewDidAppear:(BOOL)animated {

 NSUserDefaults *pickerViewSelectionDefaults = [NSUserDefaults standardUserDefaults];
[tasbeehPicker selectRow:[pickerViewSelectionDefaults integerForKey:@"picker"]
      inComponent:0 animated:YES];

[pickerViewSelectionDefaults synchronize];
[UIPicker reloadAllComponents];    

NSLog(@"Last selcted row was %d  ",[[NSUserDefaults standardUserDefaults] integerForKey:@"picker"]);

}

Answer 1

当您通过代码更新选取器时，不应调用委托(delegate)。只有当用户与选择器交互时才会调用委托(delegate)。如果您需要在两种情况下调用相同的代码，请执行以下操作:

- (void)viewDidAppear:(BOOL)animated {
    [super viewDidAppear:animated];

    [myPicker selectRow:4 inComponent:0 animated:animated];
    [self handlePickerSelection:myPicker];
}

- (void)pickerView:(UIPickerView *)pickerView didSelectRow:(NSInteger)row inComponent:(NSInteger)component {
    [self handledPickerSelection:pickerView];
}

- (void)handlePickerSelection:(UIPickerView *)pickerView {
    // process selection
}