UI Picker View未显示

Question

我已经以编程方式在我的代码中添加了一个UI Picker：

            UIPickerView *categoryList = [[UIPickerView alloc] initWithFrame:CGRectMake(10, 200, 300, 200)];  
            categoryList.showsSelectionIndicator = YES;  
            categoryList.hidden = NO;  
            categoryList.delegate = self;  

            [cell.contentView addSubview:categoryList];  

但是，当我在模拟器上运行它时，它不显示。

Answer 1

设置为textField inputView

不要添加子视图。

Answer 2

您需要实现UIPickerViewDelegate方法才能显示。

委派方法。

@Required
// returns the number of 'columns' to display.
- (NSInteger)numberOfComponentsInPickerView:(UIPickerView *)pickerView{

}

// returns the # of rows in each component..
- (NSInteger)pickerView:(UIPickerView *)pickerView numberOfRowsInComponent:   (NSInteger)component;
{
}

UIPickerViewDelegate方法用于在PickerView中显示您的视图或字符串，如下所示： -

- (NSString *)pickerView:(UIPickerView *)pickerView titleForRow:(NSInteger)row forComponent:(NSInteger)component;

更新： -

如下所示更改pickerView框架

UIPickerView *categoryList = [[UIPickerView alloc] initWithFrame:CGRectMake(cell.contentView.frame.origin.x+5, cell.contentView.frame.origin.y+5, 300, 200)];