UIPickerView選擇控件實現選擇輪播效果（轉輪效果）

UIPickerView爲用戶提供了選擇器功能，使用戶以更好的體驗方式實現數據的選擇，如圖：

 

UIPickerView控件的使用方法：（建立好根視圖：MainViewController）

 1 #import <UIKit/UIKit.h>  
 2   
 3 @interface MainViewController : UIViewController<UIPickerViewDelegate>  
 4 {  
 5     UIPickerView *pickerView;  
 6     UILabel *contentview;  
 7     NSArray *content;  // 星座;  
 8 }  
 9   
10 @end  

實現部分：

 1 - (void)viewDidLoad  
 2 {  
 3     [super viewDidLoad];  
 4     // Do any additional setup after loading the view.  
 5 }  
 6 -(void)loadView  
 7 {  
 8     UIView *view = [[UIView alloc] initWithFrame:CGRectMake(0, 0, 320, 460)];  
 9     self.view = view;  
10     view.backgroundColor = [UIColor yellowColor];  
11     [view release];  
12     // 初始化數據， 這些數據將顯示在picker中  
13     content = [[NSArray alloc] initWithObjects:@"水瓶座", @"雙魚座", @"白羊座        ", @"金牛座", @"雙子座", @"巨蟹座", @"獅子座", @"處女座", @"天秤座", @"天蠍座", @"射手座", @"白羊座",nil];  
14     // 設置選擇器  
15     pickerView = [[UIPickerView alloc] initWithFrame:CGRectMake(0, 150, 320, 216)];  
16     // 設置代理  
17     pickerView.delegate = self;  
18     pickerView.showsSelectionIndicator = YES;  
19     [self.view addSubview:pickerView];  
20     contentview = [[UILabel alloc] initWithFrame:CGRectMake(80, 80, 100, 40)];  
21     contentview.backgroundColor = [UIColor clearColor];  
22     [self.view addSubview:contentview];  
23 }  
24 #pragma mark--處理方法  
25 // 返回顯示的數列  
26 - (NSInteger)numberOfRowsInComponent:(NSInteger)component  
27 {  
28     return 1;  
29 }  
30 // 返回當前列顯示的行數  
31 - (NSInteger)pickerView:(UIPickerView *)pickerView numberOfRowsInComponent:(NSInteger)component  
32 {  
33     return [content count];  
34 }  
35 // 設置當前的內容，若是行沒有顯示則自動釋放  
36 - (NSString *)pickerView:(UIPickerView *)pickerView titleForRow:(NSInteger)row forComponent:(NSInteger)component  
37 {  
38     return [content objectAtIndex:row];  
39 }  
40 - (void)pickerView:(UIPickerView *)pickerView didSelectRow:(NSInteger)row inComponent:(NSInteger)component  
41 {  
42 //    NSString *result = [pickerView pickView:pickerView titleForRow:row forComponent:component];  
43       
44     NSString *result = nil;  
45     result = [content objectAtIndex:row];  
46     NSLog(@"result:%@", result);  
47     contentview.text = result;  
48     [result release];  
49 }  
50 - (void)didReceiveMemoryWarning  
51 {  
52     [super didReceiveMemoryWarning];  
53     // Dispose of any resources that can be recreated.  
54 }