UIKit－UIPickerView详解

UIPickerView继承图

1.UIPickerView的创建

必须实现委托delegate和数据源dataSource

UIPickerView的高度只能为三种值：

height设置区间在0～179时，UIPickerView的height为162

height设置区间在180～215时，UIPickerView的height为180

height设置区间在216～∞时，UIPickerView的height为216

UIPickerView *pickerView = [[UIPickerView alloc]initWithFrame:CGRectMake(0, 0, 300, 180)];

pickerView.dataSource = self;

pickerView.delegate = self;

2.showsSelectionIndicator    设置没设置都是一个样，无聊的可以试试

@property(nonatomic)   BOOL  showsSelectionIndicator;// default is NO

3.numberOfComponents    获取选择器的分组数

@property(nonatomic,readonly)   NSInteger  numberOfComponents;

4.UIPickerView的方法

//获取指定分组component中的行数

- (NSInteger)numberOfRowsInComponent:(NSInteger)component;

//获取单元格的Size

- (CGSize)rowSizeForComponent:(NSInteger)component;

//获取pickerView:viewForRow:forComponent:reusingView:中定义的View，当pickerView:viewForRow:forComponent:reusingView:未实现或者行或分组不可用时返回nil

- (UIView *)viewForRow:(NSInteger)row forComponent:(NSInteger)component;

//刷新所有分组

- (void)reloadAllComponents;

//刷新指定分组

- (void)reloadComponent:(NSInteger)component;

//选中指定分组中的一行

- (void)selectRow:(NSInteger)row inComponent:(NSInteger)component animated:(BOOL)animated;

//获得指定分组中选中的行

- (NSInteger)selectedRowInComponent:(NSInteger)component;

5.数据源UIPickerViewDataSource

@protocol UIPickerViewDataSource

@required

//设置分组数

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

// 设置各分组的行数

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

@end

6.委托UIPickerViewDelegate

// 设置分组的宽

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

//设置单元格的高

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

单元格中内容的展示，以下三种方法三选一

//设置显示普通字符串

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

//设置显示属性字符串，如果该方法和普通字符串方法都实现了，效果是属性字符串

- (NSAttributedString *)pickerView:(UIPickerView *)pickerView attributedTitleForRow:(NSInteger)row forComponent:(NSInteger)component NS_AVAILABLE_IOS(6_0);

//自定义显示视图

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

单元格选中时的委托方法，需要注意的是，单元格的值改变后停止滚动动画停止即调用这个方法，不需要手点击

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

7.效果图