//代理，返回UIPickerView有多少列
-(NSInteger)numberOfComponentsInPickerView:(UIPickerView *)pickerView{}


//代理，返回UIPickerView中component列有多少行
-(NSInteger)pickerView:(UIPickerView *)pickerView numberOfRowsInComponent:         (NSInteger)component


//代理，返回UIPickerView中得component列，row行的内容
-(NSString *)pickerView:(UIPickerView *)pickerView titleForRow:(NSInteger)row forComponent:(NSInteger)component


//代理  可以得到UIPickerView中当前选中的component列，row行的内容
-(void)pickerView:(UIPickerView *)pickerView didSelectRow:(NSInteger)row inComponent:(NSInteger)component

学习了......