UIPickerViewDelegate协议必须实现的方法有：
pickerView: titleForRow:forComponent，这个方法根据指定的行号返回该行的标题，也就是向用户显示的字符串。
UIPickerViewDataSource协议必须实现的方法有：
1.numberOfComponentsInPickerView，这个方法返回UIPickerView需要多少个组件。
2.pickerView: numberOfRowsInComponent，这个方法返回指定组件包含多少行。
@interface SinglePickerViewController : UIViewController <UIPickerViewDelegate, UIPickerViewDataSource> {
NSArray *pickerData;
}
@property (nonatomic,retain) IBOutlet UIPickerView *pickerView;
#pragma mark--委托协议方法
-（NSString *）pickerView:(UIPickerView *)pickerView titleForRow:(NSInteger)row forComponent:(NSInteger)component{
return [pickerData objectAtIndex:row];
}
#pragma mark--数据源协议方法
-(NSInteger)numberOfComponentsInPickerView:(UIPickerView *)pickerView{
return 1;
}
-(NSInteger)pickerView:(UIPickerView *)pickView numberOfRowsInComponent:(NSInteger)component{
return [pickerData count];
}
-(void)viewDidLoad{
NSArray *array = [[NSArray alloc] initWithObjects:@"欧洲",@"非洲",nil];
}
-(IBAciton)onClickButton:(id)sender{
NSInteger row = [pickerView selectedRowInComponent:0]; //获得第一列的选择中的行号。
NSString *selected = [array ObjectAtIndex:row];
}
(非关联）
@interface DoublePickerViewController:UIViewController<UIPickerViewDelegate,UIPickerViewDataSource>{
NSArray *array1;
NSArray *array2;
}
@property (nonatomic,retain) IBOutlet *pickerView;
#pragma mark--委托协议方法
-（NSString *）pickerView:(UIPickerView *)pickerView titleForRow:(NSInteger)row forComponent:(NSInteger)component{
if(component == 0){
return [array1 objectAtIndex:row];
} else {
return [array2 objectAtIndex:row];
}
}
#pargam mark--数据源协议方法
-(NSInteger) numberOfComponentsInPickerView：(UIPickerView *)pickerView{
return 2;
}
-(NSInteger) pickerView:(UIPickerView *)pickerView numberOfRowsInComponent:(NSInteger) component{
if(component == 0){
return [array1 count];
} else {
return [array2 count];
}
- (void)viewDidLoad {
NSArray *array1 = [[NSArray alloc] initWithObjects:@"欧洲",
@"南美", @"非洲", @"北美",
@"亚洲", @"大洋洲", nil];
NSArray *array2 = [[NSArray alloc] initWithObjects:@"足球",
@"篮球", @"羽毛球", @"乒乓球", nil];
}
-(IBAction)onClick:(id)sender{
NSInteger row1 = [pickerView selectedRowInComponent:0];
NSInteger row2 = [pickerView selectedRowInComponent:1];
NSString *str1 = [array1 ObjectAtIndex:row1];
NSString *str2 = [array2 ObjectAtIndex:row2];
NSString *title = [[NSString alloc] initWithFormat:@"你选择了%@的%@项目!",str1,str2];
UIAlertView *alert =[[UIAlertView alloc]initWithTitle:title message:@"谢谢你的选择."
delegate:nil
cancelButtonTitle:@"Ok"
otherButtonTitles:nil];
[alert show];
}
(关联）
@interface DependentPickerViewController : UIViewController<UIPickerViewDelegate,UIPickerViewDataSource>{
NSDictionary *data;
NSArray *array1;
NSArray *array2;
}
@property (nonatomic,retain) IBOutlet UIPickerView *pickerView;
-(void) viewDidLoad{
//bundle是一个目录,其中包含了程序会使用到的资源.
NSBundle *bundle = [NSBundle mainBundle];
NSString *plistPath = [bundle pathForResource:@"足球队dictionary" ofType:@"plist"];
NSDictionary *data = [[NSDictionary alloc]initWithContentsOfFile:plistPath];
//这几行代码是从statedictionary.plist属性列表文件中读取到NSDictionary对象中。
NSArray *col1= [data allkeys];
NSArray *array1 = [col1 sortedArrayUsingSelector:@selector(compare:)]; //对数据排序。
NSString *selectCol1 = [array1 objectAtIndex:0];
NSArray *array2 = [data objectForKey:selectCol1];
}
#pragma mark--委托协议方法
- (NSString *)pickerView:(UIPickerView *)pickerView
titleForRow:(NSInteger)row forComponent:(NSInteger)component {
if (component == 0) { //选择了第一列
return [array1 objectAtIndex:row];
} else {//选择了第二列
return [array2 objectAtIndex:row];
}
}
// 拖动左边的齿轮时，右边的数据相应的Reload更新。
- (void)pickerView:(UIPickerView *)pickerView didSelectRow:(NSInteger)row //委托方法是实现拾取器控件两个轮互动关键
inComponent:(NSInteger)component {
if (component == 0) {
NSString *selectCol1 = [pickerData1 objectAtIndex:row];
pickerData2 = [data objectForKey:selectCol1];
[pickerView selectRow:0 inComponent:1 animated:YES];
[pickerView reloadComponent:1]; //重新加载拾取器
}
}
pickerArray = [NSArray arrayWithObjects:@"动物",@"植物",@"石头", nil];
dicPicker = [NSDictionary dictionaryWithObjectsAndKeys:
[NSArray arrayWithObjects:@"鱼",@"鸟",@"虫子",nil], @"动物",
[NSArray arrayWithObjects:@"花",@"草",@"葵花",nil], @"植物",
[NSArray arrayWithObjects:@"疯狂的石头",@"花岗岩",@"鹅卵石", nil], @"石头",nil];