//
//  UIPickerView.h
//  UIKit
//
//  Copyright (c) 2006-2013, Apple Inc. All rights reserved.
//
#pragma - mark  和tableview一样 需要实现数据源方法和代理方法

#import <Foundation/Foundation.h>
#import <CoreGraphics/CoreGraphics.h>
#import <UIKit/UIView.h>
#import <UIKit/UITableView.h>
#import <UIKit/UIKitDefines.h>

@protocol UIPickerViewDataSource, UIPickerViewDelegate;

NS_CLASS_AVAILABLE_IOS(2_0) @interface UIPickerView : UIView <NSCoding, UITableViewDataSource>
{ 
  @private
    NSMutableArray            *_tables;
    UIView                    *_topFrame;
    NSMutableArray            *_dividers;
    NSMutableArray            *_selectionBars;
    id<UIPickerViewDataSource> _dataSource;
    id<UIPickerViewDelegate>   _delegate;
    UIView                    *_backgroundView;
    NSInteger                  _numberOfComponents;
    
    UIImageView               *_topGradient;
    UIImageView               *_bottomGradient;

    UIView                    *_foregroundView;
    CALayer                   *_maskGradientLayer;
    UIView                    *_topLineView;
    UIView                    *_bottomLineView;
  @package
    struct {
        unsigned int needsLayout:1;
        unsigned int delegateRespondsToNumberOfComponentsInPickerView:1;
        unsigned int delegateRespondsToNumberOfRowsInComponent:1;
        unsigned int delegateRespondsToDidSelectRow:1;
        unsigned int delegateRespondsToViewForRow:1;
        unsigned int delegateRespondsToTitleForRow:1;
        unsigned int delegateRespondsToAttributedTitleForRow:1;
        unsigned int delegateRespondsToWidthForComponent:1;
        unsigned int delegateRespondsToRowHeightForComponent:1;
        unsigned int showsSelectionBar:1;
        unsigned int allowsMultipleSelection:1;
        unsigned int allowSelectingCells:1;
        unsigned int soundsDisabled:1;
        unsigned int usesCheckedSelection:1;
        unsigned int skipsBackground:1;
    } _pickerViewFlags;
}

@property(nonatomic,assign) id<UIPickerViewDataSource> dataSource;                // default is nil. weak reference
@property(nonatomic,assign) id<UIPickerViewDelegate>   delegate;                  // default is nil. weak reference
@property(nonatomic)        BOOL                       showsSelectionIndicator;   // default is NO

// info that was fetched and cached from the data source and delegate
@property(nonatomic,readonly) NSInteger numberOfComponents;
- (NSInteger)numberOfRowsInComponent:(NSInteger)component;
- (CGSize)rowSizeForComponent:(NSInteger)component;

// returns the view provided by the delegate via pickerView:viewForRow:forComponent:reusingView:
// or nil if the row/component is not visible or the delegate does not implement 
// pickerView:viewForRow:forComponent:reusingView:
- (UIView *)viewForRow:(NSInteger)row forComponent:(NSInteger)component;

- (void)reloadAllComponents; // 重新加载所有的列
- (void)reloadComponent:(NSInteger)component; // 重新刷新某一列

- (void)selectRow:(NSInteger)row inComponent:(NSInteger)component animated:(BOOL)animated;  // 自动选中某行某列

- (NSInteger)selectedRowInComponent:(NSInteger)component;      // 返回选中的行号，需要传一个列号的参数

@end


@protocol UIPickerViewDataSource<NSObject>

@required
// 返回多少列
- (NSInteger)numberOfComponentsInPickerView:(UIPickerView *)pickerView;

// 返回每一列有多少行
- (NSInteger)pickerView:(UIPickerView *)pickerView numberOfRowsInComponent:(NSInteger)component;

@end


@protocol UIPickerViewDelegate<NSObject>
@optional

// component列的宽度
- (CGFloat)pickerView:(UIPickerView *)pickerView widthForComponent:(NSInteger)component;
// component 列的行高
- (CGFloat)pickerView:(UIPickerView *)pickerView rowHeightForComponent:(NSInteger)component;

// 某一行某一列显示什么文字
- (NSString *)pickerView:(UIPickerView *)pickerView titleForRow:(NSInteger)row forComponent:(NSInteger)component;
// 返回每一行带有文字属性的标题
- (NSAttributedString *)pickerView:(UIPickerView *)pickerView attributedTitleForRow:(NSInteger)row forComponent:(NSInteger)component NS_AVAILABLE_IOS(6_0);

// 某一行显示的view控件（可重用）
- (UIView *)pickerView:(UIPickerView *)pickerView viewForRow:(NSInteger)row forComponent:(NSInteger)component reusingView:(UIView *)view;
// 选中某一列的某一行就会调用这个方法（每一次只有一个可以选，所以只有一个方法）
- (void)pickerView:(UIPickerView *)pickerView didSelectRow:(NSInteger)row inComponent:(NSInteger)component;

@end