/////别忘记 .h 中写代理  <UIPickerViewDelegate,UIPickerViewDataSource>        /////UIPickerView和UIDatePicker是类似的控件，只不过UIDatePicker是日期控件，只能放日期，而UIPickerView可以放任何东西。     - (void)viewDidLoad  {      [super viewDidLoad];      _dataArray = [[NSArray alloc] initWithObjects:@"a", @"b", @"c", @"d", @"e", @"f", nil];             UIPickerView* pv = [[UIPickerView alloc] initWithFrame:CGRectMake(0, 460-216, 320, 216)];      pv.delegate = self;      pv.dataSource = self;      pv.showsSelectionIndicator = YES;      [self.view addSubview:pv];      //[pv release];  }     //多少组  - (NSInteger)numberOfComponentsInPickerView:(UIPickerView *)pickerView{      return 2;  }     //每一组多少行  - (NSInteger)pickerView:(UIPickerView *)pickerView numberOfRowsInComponent:(NSInteger)component{      if (component == 1) {          return 3;      }      if (component == 0) {          return _dataArray.count;      }      return 10;  }     //显示每一行的文本  - (NSString *)pickerView:(UIPickerView *)pickerView titleForRow:(NSInteger)row forComponent:(NSInteger)component{      if (component == 0) {          return [_dataArray objectAtIndex:row];      }      return [NSString stringWithFormat:@"%d",row];  }     - (UIView *)pickerView:(UIPickerView *)pickerView viewForRow:(NSInteger)row forComponent:(NSInteger)component reusingView:(UIView *)view{      //如果是第0组      if (component == 0) {          //如果是第0组的第0行          if (row == 0) {              //return 显示的view          }          if (row == 1) {              //          }      }      UIView* myview = [[UIView alloc] initWithFrame:CGRectMake(0, 0, 20, 20)];      myview.backgroundColor = [UIColor redColor];      return myview;  }     //选择一行就会调用这个方法  - (void)pickerView:(UIPickerView *)pickerView didSelectRow:(NSInteger)row inComponent:(NSInteger)component{      NSLog(@"选择的是第%d组，第%d行",component,row);  }