UIPickerView Properties

Key properties for configuring a UIPickerView include:

// Specifies the data source object that provides data for the picker
@property(nonatomic, weak) id<UIPickerViewDataSource> dataSource;

// Specifies the delegate object that handles display and selection events
@property(nonatomic, weak) id<UIPickerViewDelegate> delegate;

// Controls visibility of the selection indicator overlay
@property(nonatomic) BOOL showsSelectionIndicator;

// Read-only property indicating total number of components (columns)
@property(nonatomic, readonly) NSInteger numberOfComponents;

UIPickerView Methods

Essential methods for managing picker view state:

// Reloads all components with fresh data
- (void)refreshAllComponents;

// Reloads data for a specific component
- (void)refreshComponent:(NSInteger)componentIndex;

// Programmatically selects a row in a component
- (void)selectRowAtIndex:(NSInteger)rowIndex 
            inComponent:(NSInteger)componentIndex 
               anmiated:(BOOL)shouldAnimate;

// Returns currently selected row index for specified component
- (NSInteger)currentSelectedRowInComponent:(NSInteger)componentIndex;

Data Source Protocol Methods

Required methods for providing data to UIPickerView:

// Returns number of columns (components) in picker
- (NSInteger)numberOfComponentsInPickerView:(UIPickerView *)picker;

// Returns number of rows for specified component
- (NSInteger)pickerView:(UIPickerView *)picker 
numberOfRowsInComponent:(NSInteger)componentIndex;

Delegate Protocol Methods

Methods for customizing appearance and handling interactions:

// Defines width for each component
- (CGFloat)pickerView:(UIPickerView *)picker 
    widthForComponent:(NSInteger)componentIndex;

// Defines row height for each component
- (CGFloat)pickerView:(UIPickerView *)picker 
   rowHeightForComponent:(NSInteger)componentIndex;

// Provides text content for specific row
- (NSString *)pickerView:(UIPickerView *)picker 
             titleForRow:(NSInteger)rowIndex 
            forComponent:(NSInteger)componentIndex;

// Provides custom view for specific row (alternative too text)
- (UIView *)pickerView:(UIPickerView *)picker 
            viewForRow:(NSInteger)rowIndex 
          forComponent:(NSInteger)componentIndex 
           reuseView:(UIView *)existingView;

// Called when user selects a row
- (void)pickerView:(UIPickerView *)picker 
      didSelectRow:(NSInteger)rowIndex 
       inComponent:(NSInteger)componentIndex;

UIDatePicker Configuration

Core properties for date picker customization:

// Sets the display mode (date, time, dateAndTime, countDownTimer)
@property (nonatomic) UIDatePickerMode selectionMode;

// Sets locale to regional formatting
@property (nonatomic, strong) NSLocale *regionalLocale;

Handling UIDatePicker Events

Since UIDatePicker inherits from UIControl, use target-action pattern for event handling:

// Example: Adding target for value changes
[datePickerInstance addTarget:self 
                       action:@selector(dateSelectionChanged:) 
             forControlEvents:UIControlEventValueChanged];

// Handler method implementation
- (void)dateSelectionChanged:(UIDatePicker *)sender {
    NSDate *selectedDate = sender.date;
    // Process selected date
}