[新手学ios]第三天:使用tab Bar Controller 实现多组件选择器和组关联(plist和数据绑定)

最新推荐文章于 2023-01-13 14:22:32 发布

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本文详细解释了如何实现双列选择器，并利用 plist 文件作为数据源。介绍了数据绑定过程，包括如何加载数据到 dictionary 和相应更新组件状态。此外，还展示了如何根据选择项动态调整 UI 的宽度。

在第上一篇中,我们学习了如何实现单组件选择器.

这一节主要是针对一些新的知识点进行说明,如果觉得我思维过快,请看上一篇.

1.double行选择器.

-(NSInteger)pickerView:(UIPickerView *)pickerView numberOfRowsInComponent:(NSInteger)component
{
    if (component == 0) {
        return [myFirstNameArray count];
    }
    
    return [myLastNameArray count];
   
}

-(NSString *)pickerView:(UIPickerView *)pickerView titleForRow:(NSInteger)row forComponent:(NSInteger)component
{
    if (component == 0)
        return [self.myFirstNameArray objectAtIndex:row];

    return [self.myLastNameArray objectAtIndex:row];
        

}

由于这个是两列,所以第一列index = 0,第二列是 1. 对应的数据显示我就不说了.

2.数据绑定和plist 作为数据源.

#define KStateComponent 0
#define KzipComponet 1


@interface BIDDependentComponentPickerViewController : UIViewController<UIPickerViewDelegate,UIPickerViewDataSource>

@property (strong, nonatomic) IBOutlet UIPickerView *picker;

@property (strong,nonatomic)NSDictionary *stateZips;
@property (strong,nonatomic)NSArray *states;
@property (strong,nonatomic)NSArray *zips;
- (IBAction)ButtonPressed:(id)sender;

因为 plist 文件存放的时 state - zips 是 value-key 对,所以我们需要使用dictionary来接收.

下面的代码就是 dictionary的加载.

- (void)viewDidLoad
{
    [super viewDidLoad];
    
    NSBundle *bundle =[NSBundle mainBundle];
    NSURL *plistURL = [bundle URLForResource:@"statedictionary" withExtension:@"plist" ];
    //得到一个路径.
    NSDictionary *dictionary = [[NSDictionary alloc]initWithContentsOfURL:plistURL];
    //加载
    self.stateZips = dictionary;
    
    NSArray *compoments = [self.stateZips allKeys];//得到所有的key(state).
    NSArray *sorted = [compoments sortedArrayUsingSelector:@selector(compare:)];
    
    self.states = sorted;
    
    NSString *selectedState = [self.states objectAtIndex:0];
    
    NSArray *array  = [stateZips objectForKey:selectedState];
    self.zips = array;
    // Do any additional setup after loading the view from its nib.
}

3.新增的协议函数.

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

{

if (component == KStateComponent) {

NSString *selectedState = [self.states objectAtIndex:row];

NSArray *array = [stateZips objectForKey:selectedState];

self.zips = array;

//当我重新加载了zips之后,我们也需要相应的加载 kzipcomponent.

[picker selectRow:0 inComponent:KzipComponet animated:YES];

[picker reloadComponent:KzipComponet];

}

-(CGFloat)pickerView:(UIPickerView *)pickerView widthForComponent:(NSInteger)component
{
    if (component == KStateComponent)
        return 200;
    return 90;
}

这段代码的意思是:如果我们发现行列的宽和高搭配的不是很合理,我们就需要主动的设定.

还有一个设置高的协议函数.