如何为此选择器视图提供数据源

Question

我在这里以编程方式添加了一个pickerview

 - (void)viewDidLoad {
        [super viewDidLoad];
        CGRect pickerFrame = CGRectMake(0,280,321,200);

        UIPickerView *myPickerView = [[UIPickerView alloc] init]; //Not sure if this is the proper allocation/initialization procedure

        //Set up the picker view as you need it

        //Set up the display frame
        myPickerView.frame = pickerFrame; //I recommend using IB just to get the proper width/height dimensions

        //Add the picker to the view
        [self.view addSubview:myPickerView];
    }

但现在我需要实际让它显示内容,并以某种方式找出它何时发生变化以及它变为什么值.我该怎么做呢？

Answer 1

在.h文件中放置此代码

@interface RootVC : UIViewController <UIPickerViewDelegate, UIPickerViewDataSource>

将数据源和委托分配给选择器

// this view controller is the data source and delegate
myPickerView.delegate = self;
myPickerView.dataSource = self;

使用以下委托和datasouce方法

- (void)pickerView:(UIPickerView *)pickerView didSelectRow:(NSInteger)row inComponent:(NSInteger)component
{

}

- (CGFloat)pickerView:(UIPickerView *)pickerView widthForComponent:(NSInteger)component
{
    return 200;
}

- (CGFloat)pickerView:(UIPickerView *)pickerView rowHeightForComponent:(NSInteger)component
{
    return 50;
}

- (NSString *)pickerView:(UIPickerView *)pickerView titleForRow:(NSInteger)row forComponent:(NSInteger)component
{
    NSString *returnStr = @"";
    if (pickerView == myPickerView)
    {       
        returnStr = [[levelPickerViewArray objectAtIndex:row] objectForKey:@"nodeContent"];
    }

    return returnStr;
}

- (NSInteger)pickerView:(UIPickerView *)pickerView numberOfRowsInComponent:(NSInteger)component
{
    if (pickerView == myPickerView)
    {
        return [levelPickerViewArray count];
    }
}

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