iOS

前言

	NS_CLASS_AVAILABLE_IOS(2_0) __TVOS_PROHIBITED @interface UIPickerView : UIView <NSCoding, UITableViewDataSource>
	@available(iOS 2.0, *)                      public class UIPickerView : UIView, NSCoding, UITableViewDataSource 

• 选择框可以让用户以滑动的方式选择值。

1、UIPickerView 的创建

• 遵守协议 UIPickerViewDataSource, UIPickerViewDelegate

• Objective-C

  	// 实例化 UIPickerView 对象
  	UIPickerView *pickerView = [[UIPickerView alloc] init];
  
  	// 设置代理
  	pickerView.dataSource = self;
  	pickerView.delegate = self;
  
  	// 将 pickerView 添加到屏幕
  	[self.view addSubview:pickerView];
  
  	// 设置列数，必须设置，UIPickerViewDataSource 协议方法
  	- (NSInteger)numberOfComponentsInPickerView:(UIPickerView *)pickerView {
  
  	    return 3;
  	}
  	
  	// 设置行数	，必须设置，UIPickerViewDataSource 协议方法
  	- (NSInteger)pickerView:(UIPickerView *)pickerView numberOfRowsInComponent:(NSInteger)component {
  
  	    return 10;
  	}
  	
  	// 设置各行内容，必须设置，UIPickerViewDelegate 方法
  	- (NSString *)pickerView:(UIPickerView *)pickerView titleForRow:(NSInteger)row forComponent:(NSInteger)component {
  
  	    return [NSString stringWithFormat:@"%li行 - %li列", row, component];
  	}
  

• Swift

  	// 实例化 UIPickerView 对象
  	let pickerView:UIPickerView = UIPickerView()
  
  	// 设置代理
  	pickerView.dataSource = self
  	pickerView.delegate = self
  
  	// 将 pickerView 添加到屏幕
  	self.view.addSubview(pickerView)
  
  	// 设置列数，必须设置，UIPickerViewDataSource 协议方法
  	func numberOfComponentsInPickerView(pickerView: UIPickerView) -> Int {
  
  	    return 3
  	}
  	    
  	// 设置行数，必须设置，UIPickerViewDataSource 协议方法
  	func pickerView(pickerView: UIPickerView, numberOfRowsInComponent component: Int) -> Int {
  	    
  	    return 10
  	}
  	    
  	// 设置各行内容，必须设置，UIPickerViewDelegate 方法
  	func pickerView(pickerView: UIPickerView, titleForRow row: Int, forComponent component: Int) -> String? {
  	    
  	    return String(format: "%li行 - %li列", row, component)
  	}
  

2、UIPickerView 的设置

• Objective-C

  	// 设置默认值
  	[pickerView selectRow:1 inComponent:0 animated:YES];      // 第 0 列的默认值为 1
  	[pickerView selectRow:2 inComponent:1 animated:YES];      // 第 1 列的默认值为 2
  	[pickerView selectRow:3 inComponent:2 animated:YES];      // 第 2 列的默认值为 3
  	    
  	// 设置 frame
  	/*
  		高度只有三个值：162, 180 和 216，默认为 216，设置为其它的值无效
  	*/
  	pickerView.frame = CGRectMake(10, 30, self.view.bounds.size.width - 20, 162);
  
  	// 设置位置
  	pickerView.center = self.view.center;
  	    
  	// 设置背景颜色
  	pickerView.backgroundColor = [UIColor orangeColor];
  	    
  	// 是否显示指示器
  	/*
  		default is NO
  	*/
  	pickerView.showsSelectionIndicator = YES;
  
  	// 刷新指定的列
  	[pickerView reloadComponent:0];
  	    
  	// 刷新所有的列
  	[pickerView reloadAllComponents];
  	    
  	// 获取列数，只读
  	NSInteger numberOfComponents = pickerView.numberOfComponents;
  
  	// 获取指定列的行数
  	NSInteger numberOfRows = [pickerView numberOfRowsInComponent:0];
  	  	
  	// 获取指定行的尺寸
  	CGSize rowSize = [pickerView rowSizeForComponent:0];
  	   	
  	// 获取指定列被选中的行数索引
  	NSInteger selectedIndex = [pickerView selectedRowInComponent:0];
  	   	
  	// 获取指定行列的视图
  	UIView *view = [pickerView viewForRow:3 forComponent:0];
  	
  	// 设置列宽
  	/*
  		不设置时为默认宽度，UIPickerViewDelegate 方法
  	*/
  	- (CGFloat)pickerView:(UIPickerView *)pickerView widthForComponent:(NSInteger)component {
  
  	    return 50;
  	}
  	
  	// 设置行高
  	/*
  		不设置时为默认高度 32，UIPickerViewDelegate 方法
  	*/
  	- (CGFloat)pickerView:(UIPickerView *)pickerView rowHeightForComponent:(NSInteger)component {
  	    
  	    return 50;
  	}
  

• Swift

  	// 设置默认值
  	pickerView.selectRow(1, inComponent: 0, animated: true)      // 第 0 列的默认值为 1
  	pickerView.selectRow(2, inComponent: 1, animated: true)      // 第 1 列的默认值为 2
  	pickerView.selectRow(3, inComponent: 2, animated: true)      // 第 2 列的默认值为 3
  	    
  	// 设置 frame
  	/*
  		高度只有三个值：162, 180 和 216，默认为 216，设置为其它的值无效
  	*/
  	pickerView.frame = CGRectMake(10, 30, self.view.bounds.size.width - 20, 162)
  	    
  	// 设置位置
  	pickerView.center = self.view.center
  	    
  	// 设置背景颜色
  	pickerView.backgroundColor = UIColor.orangeColor()
  	    
  	// 是否显示指示器
  	/*
  		default is NO
  	*/
  	pickerView.showsSelectionIndicator = true
  	    
  	// 刷新指定的列
  	pickerView.reloadComponent(0)
  	    
  	// 刷新所有的列
  	pickerView.reloadAllComponents()
  	    
  	// 获取列数，只读
  	let numberOfComponents:Int = pickerView.numberOfComponents
  	  	
  	// 获取指定列的行数
  	let numberOfRows:Int = pickerView.numberOfRowsInComponent(0)
  	   	
  	// 获取指定行的尺寸
  	let rowSize:CGSize = pickerView.rowSizeForComponent(0)
  	   	
  	// 获取指定列被选中的行数索引
  	let selectedIndex:Int = pickerView.selectedRowInComponent(0)
  	   	
  	// 获取指定行列的视图
  	let view:UIView? = pickerView.viewForRow(3, forComponent: 0)
  	
  	// 设置列宽
  	/*
  		不设置时为默认宽度，UIPickerViewDelegate 方法
  	*/
  	func pickerView(pickerView: UIPickerView, widthForComponent component: Int) -> CGFloat {
  	    
  	    return 50
  	}
  	    
  	// 设置行高
  	/*
  		不设置时为默认高度 32，UIPickerViewDelegate 方法
  	*/
  	func pickerView(pickerView: UIPickerView, rowHeightForComponent component: Int) -> CGFloat {
  	    
  	    return 50
  	}
  

3、UIPickerViewDataSource 协议方法

• Objective-C

  	// 设置列数
  	- (NSInteger)numberOfComponentsInPickerView:(UIPickerView *)pickerView {
  	
  	}
  	
  	// 设置行数
  	- (NSInteger)pickerView:(UIPickerView *)pickerView numberOfRowsInComponent:(NSInteger)component {
  	
  	}
  

• Swift

  	// 设置列数
  	func numberOfComponentsInPickerView(pickerView: UIPickerView) -> Int {
  	
  	}
  	
  	// 设置行数
  	func pickerView(pickerView: UIPickerView, numberOfRowsInComponent component: Int) -> Int {
  	
  	}
  

4、UIPickerViewDelegate 协议方法

• Objective-C

  	// 设置各行内容为 字符串
  	- (NSString *)pickerView:(UIPickerView *)pickerView titleForRow:(NSInteger)row forComponent:(NSInteger)component {
  	
  	}
  	
  	// 设置各行内容为 NSAttributedString 型字符串
  	- (NSAttributedString *)pickerView:(UIPickerView *)pickerView attributedTitleForRow:(NSInteger)row forComponent:(NSInteger)component {
  	
  	}
  	
  	// 设置各行内容为 view
  	- (UIView *)pickerView:(UIPickerView *)pickerView viewForRow:(NSInteger)row forComponent:(NSInteger)component reusingView:(UIView *)view {
  	
  	}
  	
  	// 设置列宽
  	- (CGFloat)pickerView:(UIPickerView *)pickerView widthForComponent:(NSInteger)component {
  	
  	}
  	
  	// 设置行高
  	- (CGFloat)pickerView:(UIPickerView *)pickerView rowHeightForComponent:(NSInteger)component {
  	
  	}
  	
  	// 检测行的选择状态，在滑动停止后触发
  	- (void)pickerView:(UIPickerView *)pickerView didSelectRow:(NSInteger)row inComponent:(NSInteger)component {
  	    
  	}
  

• Swift

  	// 设置各行内容为 字符串
  	func pickerView(pickerView: UIPickerView, titleForRow row: Int, forComponent component: Int) -> String? {
  	
  	}
  	
  	// 设置各行内容为 NSAttributedString 型字符串
  	func pickerView(pickerView: UIPickerView, attributedTitleForRow row: Int, forComponent component: Int) -> NSAttributedString? {
  	
  	}
  	
  	// 设置各行内容为 view
  	func pickerView(pickerView: UIPickerView, viewForRow row: Int, forComponent component: Int, reusingView view: UIView?) -> UIView {
  	
  	}
  	
  	// 设置列宽
  	func pickerView(pickerView: UIPickerView, widthForComponent component: Int) -> CGFloat {
  	
  	}
  	
  	// 设置行高
  	func pickerView(pickerView: UIPickerView, rowHeightForComponent component: Int) -> CGFloat {
  	
  	}
  	    
  	// 检测行的选择状态，在滑动停止后触发
  	func pickerView(pickerView: UIPickerView, didSelectRow row: Int, inComponent component: Int) {
  
  	}