显示DatePicker的当前日期

NSDate*selected= [datepicker date];   

NSString*message = [[NSStringalloc]initWithFormat:@“选择的日期和时间是：%@”, selected];

UIAlertView*alert = [[UIAlertViewalloc] initWithTitle:@"日期和时间" message:message delegate: nil cancelButtonTitle:@"关闭"  otherButtonTitles:nil];

[alert show];

设置DatePicker为当前时间

 NSDate *now = [[NSDatealloc]init];

[datepickersetDate:nowanimated:YES];

单列PickerView的核心事件方法

//  返回列表数

- (NSInteger)pickerView:(UIPickerView *)pickerView

numberOfRowsInComponent:(NSInteger)component {

    return [pickerData count];

}

//  返回每个列表项的文本

- (NSString *)pickerView:(UIPickerView *)pickerView

   titleForRow:(NSInteger)row

  forComponent:(NSInteger)component {

    return [pickerDataobjectAtIndex:row];

}

双列PickerView的核心事件(1)

//  返回两列

- (NSInteger)numberOfComponentsInPickerView:(UIPickerView *)pickerView {

    return 2;

}

//  返回每一列的列表项数

- (NSInteger)pickerView:(UIPickerView *)pickerView

numberOfRowsInComponent:(NSInteger)component {

    if (component == LEFT)

        return [self.leftArray count];

    return [self.rightArray count];

}

双列PickerView的核心事件（2）

- (NSString *)pickerView:(UIPickerView *)pickerView

   titleForRow:(NSInteger)row

  forComponent:(NSInteger)component {

    if (component == LEFT)

        return [self.leftArrayobjectAtIndex:row];

    return [self.rightArrayobjectAtIndex:row];

}

获取当前双列的列表项

NSIntegerleftRow = [pickerviewselectedRowInComponent:

                     LEFT];

NSIntegerrightRow = [pickerviewselectedRowInComponent:

                      RIGHT];

NSString *left = [leftArrayobjectAtIndex:leftRow];

NSString *right = [rightArrayobjectAtIndex:rightRow];

//  获取列表项（两列）

NSString *message = [[NSStringalloc] initWithFormat:

                     @"Left: %@   Right:%@", left, right];

获取当前双列的列表项

NSIntegerleftRow = [pickerviewselectedRowInComponent:

                     LEFT];

NSIntegerrightRow = [pickerviewselectedRowInComponent:

                      RIGHT];

NSString *left = [leftArrayobjectAtIndex:leftRow];

NSString *right = [rightArrayobjectAtIndex:rightRow];

//  获取列表项（两列）

NSString *message = [[NSStringalloc] initWithFormat:

                     @"Left: %@   Right:%@", left, right];