UIPickerView和UIDataPicker

 一.UIPickerView

    1.UIPickerView的常见属性

// 数据源(用来告诉UIPickerView有多少列多少行)
@property(nonatomic,assign) id<UIPickerViewDataSource> dataSource;
// 代理(用来告诉UIPickerView每1列的每1行显示什么内容,监听UIPickerView的选择)
@property(nonatomic,assign) id<UIPickerViewDelegate>   delegate;
// 是否要显示选中的指示器
@property(nonatomic)        BOOL                       showsSelectionIndicator;
// 一共有多少列
@property(nonatomic,readonly) NSInteger numberOfComponents;

    2.UIPickerView的常见方法

// 从新刷新全部列
- (void)reloadAllComponents;
// 从新刷新第component列
- (void)reloadComponent:(NSInteger)component;

// 主动选中第component列的第row行
- (void)selectRow:(NSInteger)row inComponent:(NSInteger)component animated:(BOOL)animated;

// 得到第component列的当前选中的行号
- (NSInteger)selectedRowInComponent:(NSInteger)component;

    3.数据源方法(UIPickerViewDataSource)

//  一共有多少列
- (NSInteger)numberOfComponentsInPickerView:(UIPickerView *)pickerView;
//  第component列一共有多少行
- (NSInteger)pickerView:(UIPickerView *)pickerView numberOfRowsInComponent:(NSInteger)component;

    4.代理方法(UIPickerViewDelegate)

//  第component列的宽度是多少
- (CGFloat)pickerView:(UIPickerView *)pickerView widthForComponent:(NSInteger)component;
//  第component列的行高是多少
- (CGFloat)pickerView:(UIPickerView *)pickerView rowHeightForComponent:(NSInteger)component;

//  第component列第row行显示什么文字
- (NSString *)pickerView:(UIPickerView *)pickerView titleForRow:(NSInteger)row forComponent:(NSInteger)component;

//  第component列第row行显示怎样的view(内容)
- (UIView *)pickerView:(UIPickerView *)pickerView viewForRow:(NSInteger)row forComponent:(NSInteger)component reusingView:(UIView *)view;

//  选中了pickerView的第component列第row行
- (void)pickerView:(UIPickerView *)pickerView didSelectRow:(NSInteger)row inComponent:(NSInteger)component;

二.UIDatePicker

    1.常见属性

// datePicker的显示模式
@property (nonatomic) UIDatePickerMode datePickerMode;
// 显示的区域语言
@property (nonatomic, retain) NSLocale *locale;

    2.监听UIDatePicker的选择

     由于UIDatePicker继承自UIControl,因此经过addTarget:...监听