UIPickerView 出现无法解释的警告

Question

我在我的应用程序中实现了一个简单的 UIPickerView，并且不断收到警告，提示我无法解释不完整的实现和“协议中的方法未完成”。我浏览了一堆例子，但无法弄清楚我错过了什么。

是我的代码：

.h.m

@interface ViewTestViewController : UIViewController <UITableViewDelegate, UITableViewDataSource, UIPageViewControllerDataSource, UIPageViewControllerDataSource> {

 UIPickerView *pickerView;
NSMutableArray *pickerList;

....

}
@property (nonatomic, retain) IBOutlet UIPickerView *pickerView;
@property (nonatomic, retain) NSMutableArray *pickerList;


@end

这

- (void)viewDidLoad
{
[super viewDidLoad];

 …

//PICKER AREA
pickerList = [[NSMutableArray alloc] init];
[pickerList addObject:@"aaa"];
[pickerList addObject:@"bbb"];

CGRect pickerFrame = CGRectMake(0, 200, 0, 0);
pickerView = [[UIPickerView alloc] initWithFrame:pickerFrame];
pickerView.showsSelectionIndicator = YES;    

}

-(IBAction)showPicker:(id)sender {

 [self.view addSubview:pickerView];

}

-(NSInteger)numberOfComponentsInPickerView:(UIPickerView *)thePickerView
{
return 1;
}

-(NSInteger)pickerView:(UIPickerView *)thePickerView numberOfRowsInComponent:(NSInteger)component
 {
return [pickerList count];
}

-(NSString *)pickerView:(UIPickerView *)thePickerView titleForRow:(NSInteger)row forComponent:(NSInteger)component
{
return [pickerList objectAtIndex:row];
}

-(void)pickerView:(UIPickerView *)thePickerView didSelectRow:(NSInteger)row inComponent:(NSInteger)component
{
NSLog(@"Selected item: %@ index of selected item: %i", [pickerList objectAtIndex:row], row);
}

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

return 200;
}

Answer 1

您需要遵守 .h 中的 UIPickerViewDelegate 和 UIPickerViewDataSource，就像您对 UITableViewDelegate、UITableViewDataSource 等所做的那样（目前还没有）

@interface ViewTestViewController : UIViewController <UIPickerViewDataSource, UIPickerViewDelegate, UITableViewDelegate, UITableViewDataSource, UIPageViewControllerDataSource, UIPageViewControllerDataSource> {

另外，请确保您设置 <创建时将 code>self 作为选取器视图委托和数据源：

//PICKER AREA
pickerList = [[NSMutableArray alloc] init];
[pickerList addObject:@"aaa"];
[pickerList addObject:@"bbb"];

CGRect pickerFrame = CGRectMake(0, 200, 0, 0);
pickerView = [[UIPickerView alloc] initWithFrame:pickerFrame];
pickerView.showsSelectionIndicator = YES; 
pickerView.dataSource = self;
pickerView.delegate = self;

Answer 2

在您的 .h 文件中，您声明自己遵守这些协议：

<UITableViewDelegate, UITableViewDataSource, UIPageViewControllerDataSource, UIPageViewControllerDataSource>

每个协议都涉及一些您必须实现的方法（有关详细信息，请参阅每个协议的文档）。如果您没有实现所有必需的方法，您将收到此警告。