UIPickerView.h

//

//  UIPickerView.h

//  UIKit

//

//  Copyright (c) 2006-2012, Apple Inc. All rights reserved.

//

#import<Foundation/Foundation.h>

#import<CoreGraphics/CoreGraphics.h>

#import<UIKit/UIView.h>

#import<UIKit/UITableView.h>

#import<UIKit/UIKitDefines.h>

@protocolUIPickerViewDataSource, 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;

 @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 delegateRespondsToCheckableForRow: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;

// Reloading whole view or single component

- (void)reloadAllComponents;

- (void)reloadComponent:(NSInteger)component;

// selection. in this case, it means showing the appropriate row in the middle

- (void)selectRow:(NSInteger)row inComponent:(NSInteger)component animated:(BOOL)animated; // scrolls the specified row to center.

- (NSInteger)selectedRowInComponent:(NSInteger)component;                                  // returns selected row. -1 if nothing selected

@end

@protocol UIPickerViewDataSource<NSObject>

@required

// returns the number of 'columns' to display.

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

// returns the # of rows in each component..

- (NSInteger)pickerView:(UIPickerView *)pickerView numberOfRowsInComponent:(NSInteger)component;

@end

@protocol UIPickerViewDelegate<NSObject>

@optional

// returns width of column and height of row for each component. 

- (CGFloat)pickerView:(UIPickerView *)pickerView widthForComponent:(NSInteger)component;

- (CGFloat)pickerView:(UIPickerView *)pickerView rowHeightForComponent:(NSInteger)component;

// these methods return either a plain NSString, a NSAttributedString, or a view (e.g UILabel) to display the row for the component.

// for the view versions, we cache any hidden and thus unused views and pass them back for reuse. 

// If you return back a different object, the old one will be released. the view will be centered in the row rect  

- (NSString *)pickerView:(UIPickerView *)pickerView titleForRow:(NSInteger)row forComponent:(NSInteger)component;

- (NSAttributedString *)pickerView:(UIPickerView *)pickerView attributedTitleForRow:(NSInteger)row forComponent:(NSInteger)componentNS_AVAILABLE_IOS(6_0); // attributed title is favored if both methods are implemented

- (UIView *)pickerView:(UIPickerView *)pickerView viewForRow:(NSInteger)row forComponent:(NSInteger)component reusingView:(UIView *)view;

- (void)pickerView:(UIPickerView *)pickerView didSelectRow:(NSInteger)row inComponent:(NSInteger)component;

@end