UIPickerView(滚动选择控制器)
最后更新于：2022-04-01 06:59:17
1.UIPickerView的宽度和高度是固定的,纵向是320*216,横向是568*162
2.属性:
@property(nonatomic,readonly)NSInteger numberOfComponents; // 选择框的行数
@property(nonatomic,assign)idUIPickerViewDataSource> dataSource; (类似于UITableView)
@property(nonatomic,assign)idUIPickerViewDelegate>delegate; (类似于UITableView)
(BOOL)showsSelectionIndicator// 是否显示选择指示器 ,即是一个蓝色的条
~~~
pickerView = [[UIPickerView alloc] initWithFrame:CGRectMake(0, 0, 320, 216)];
// 指定Delegate
pickerView.delegate=self;
// 显示选中框
pickerView.showsSelectionIndicator=YES;
[self.view addSubview:pickerView];
~~~
以上可以在视图显示一个选取器，但是内容空白，pickerView.showsSelectionIndicator=YES;是这只当前选取器所选中的内容：
选取器上显示数据，必须依赖两个协议，UIPickerViewDelegate和UIPickerViewDataSource，把他们添加到ViewController.h文件中
~~~
#import <UIKit/UIKit.h>
@interface ViewController : UIViewController<UIPickerViewDelegate,UIPickerViewDataSource>
{
UIPickerView *pickerView;
NSArray *pickerData;
}
@end
~~~
3.然后在.m文件的ViewDidLoad中初始化界面
~~~
- (void)viewDidLoad
{
[super viewDidLoad];
// Do any additional setup after loading the view, typically from a nib.
pickerView = [[UIPickerView alloc] initWithFrame:CGRectMake(0, 0, 320, 216)];
// 指定Delegate
pickerView.delegate=self;
// 显示选中框
pickerView.showsSelectionIndicator=YES;
[self.view addSubview:pickerView];
NSArray *dataArray = [[NSArray alloc]initWithObjects:@"许嵩",@"周杰伦",@"梁静茹",@"许飞",@"凤凰传奇",@"阿杜",@"方大同",@"林俊杰",@"胡夏",@"邱永传", nil];
pickerData=dataArray;
// 添加按钮
CGRect frame = CGRectMake(120, 250, 80, 40);
UIButton *selectButton = [UIButton buttonWithType:UIButtonTypeRoundedRect];
selectButton.frame=frame;
[selectButton setTitle:@"SELECT" forState:UIControlStateNormal];
[selectButton addTarget:self action:@selector(buttonPressed:) forControlEvents:UIControlEventTouchUpInside];
[self.view addSubview:selectButton];
}
~~~
4.实现UIPickerView的代理方法，将数据显示在选取器上所需要几个方法
~~~
#pragma mark -
#pragma mark Picker Date Source Methods
//返回显示的列数
-(NSInteger)numberOfComponentsInPickerView:(UIPickerView *)pickerView
{
return 1;
}
//返回当前列显示的行数
-(NSInteger)pickerView:(UIPickerView *)pickerView numberOfRowsInComponent:(NSInteger)component
{
return [pickerData count];
}
#pragma mark Picker Delegate Methods
//返回当前行的内容,此处是将数组中数值添加到滚动的那个显示栏上
-(NSString*)pickerView:(UIPickerView *)pickerView titleForRow:(NSInteger)row forComponent:(NSInteger)component
{
return [pickerData objectAtIndex:row];
}
~~~
前两个是数据源的代理方法，一个是返回列，有几个选取器就返回几，第二个是设置选取器有多少行，因为就这一个选取器，所以直接返回行数，即数组元素个数多少；第三个代理方法是将数组元素添加到了选取器上面显示；
说一下两个协议实例方法,参考[http://www.cnblogs.com/edsioon/](http://www.cnblogs.com/edsioon/)
UIPickerViewDelegate[中的实例方法](http://www.cnblogs.com/edsioon/archive/2012/03/27/2418914.html)
// 当用户选择某个row时
- (void) pickerView: (UIPickerView *)pickerView didSelectRow: (NSInteger)row inComponent: (NSInteger)component
// 当其在绘制row内容,需要row的高度时
- (CGFloat) pickerView:(UIPickerView *)pickerView rowHeightForComponent: (NSInteger) component
// 返回指定component.row显示的文本
- (NSString *)pickerView:(UIPickerView *)pickerView titleForRow:(NSInteger)row forComponent:(NSInteger) component
// 当picker view需要给指定的component.row指定view时,调用此函数.返回值为用作row内容的view
- (UIView *)pickerView: (UIPickerView *)pickerView view ForRow:(NSInteger) row forComponent:(NSInteger) component reusingView:(UIView *) view
// row的宽度
- (CGFloat)pickerView: (UIPickerView *)pickerView widthForComponent:(NSInteger) component
[UIPickerViewDataSource](http://www.cnblogs.com/edsioon/archive/2012/03/27/2418919.html)[中的实例方法](http://www.cnblogs.com/edsioon/archive/2012/03/27/2418919.html)
按照官方文档的说法,UIPickerViewDataSource这个协议仅有的功能就是提供picker view中component的个数和各个component中的row的个数,虽然名为datasource,但是它工作于MVC的C中
本协议仅有两个实例方法,均需要实现:
// 返回列数
- (NSInteger)numberOfComponentsInPickerView:(UIPickerView *)pickerView
// 返回每一列对应的行数
- (NSInteger) pickerView:(UIPickerView *) pickerView numberOfRowsInComponent:(NSInteger) component
5.关于按钮响应事件，关于按钮的形成和添加响应事件不再提，前面都有，
~~~
(void) buttonPressed:(id)sender
{
NSInteger row =[pickerView selectedRowInComponent:0];
NSString *selected = [pickerData objectAtIndex:row];
NSString *message = [[NSString alloc] initWithFormat:@"你选择的是:%@",selected];
UIAlertView *alert = [[UIAlertView alloc] initWithTitle:@"提示"
message:message
delegate:self
cancelButtonTitle:@"OK"
otherButtonTitles: nil];
[alert show];
}
~~~
@UIPickerView还有其他实例方法
// 获取指定列的行数
- (NSInteger) numberOfRowsInComponent:(NSInteger)component
// 刷新所有的列
- (void) reloadAllComponents
// 刷新指定的列
- (void) reloadComponent: (NSInteger) component
- (CGSize) rowSizeForComponent: (NSInteger) component
// 获取某列选择的行数
- (NSInteger) selectedRowInComponent: (NSInteger) component
// 选择一行
- (void) selectRow: (NSInteger)row inComponent: (NSInteger)component animated: (BOOL)animated
- (UIView *) viewForRow: (NSInteger)row forComponent: (NSInteger)component
附上源代码: [http://download.csdn.net/detail/duxinfeng2010/4410909](http://download.csdn.net/detail/duxinfeng2010/4410909)