iOS开发之使用Picker View的案例

#import "YYViewController.h"

//遵守数据源和代理协议
@interface YYViewController ()
/**
 *  水果
 */
@property (strong, nonatomic) IBOutlet UILabel *fruitLab;
/**
 *  主菜
 */
@property (strong, nonatomic) IBOutlet UILabel *stapleLab;
/**
 *  饮料
 */
@property (strong, nonatomic) IBOutlet UILabel *drinkLab;
/**
 *  保存所有的数据
 */
@property(nonatomic,strong)NSArray *foods;
@property (weak, nonatomic) IBOutlet UIPickerView *pickerView;
- (IBAction)randomFood:(id)sender;

@end

- (void)viewDidLoad
{
    [super viewDidLoad];
   
    //在这里设置下方数据刷新部分的初始显示
    for (int component = 0; component         [self pickerView:nil didSelectRow:0 inComponent:component];
    }
}

#pragma mark-使用懒加载，把数据信息加载进来
-(NSArray *)foods
{
    if (_foods==nil) {
        NSString *fullpath=[[NSBundle mainBundle]pathForResource:@"foods.plist" ofType:nil];
        NSArray *arrayM=[NSArray arrayWithContentsOfFile:fullpath];
        _foods=arrayM;
    }
    return _foods;
}

#pragma mark-处理随机按钮的点击事件
- (IBAction)randomFood:(id)sender {
   
    // 让pickerView主动选中某一行
    // 让pickerView选中inComponent列的Row行
    //    [self.pickerView selectRow:1 inComponent:0 animated:YES];
   
    /*
     [self.pickerView selectRow: arc4random() % 12 inComponent:0 animated:YES];
     [self.pickerView selectRow: arc4random() % 15 inComponent:1 animated:YES];
     [self.pickerView selectRow: arc4random() % 10 inComponent:2 animated:YES];
     */
   
    //    [self.foods objectAtIndex:0]; == self.foods[0];
    //    [self.foods[0] count];
   
    /*
     // 根据每一列的元素个数生成随机值
     [self.pickerView selectRow: arc4random() % [self.foods[0] count] inComponent:0 animated:YES];
     [self.pickerView selectRow: arc4random() % [self.foods[1] count] inComponent:1 animated:YES];
     [self.pickerView selectRow: arc4random() % [self.foods[2] count] inComponent:2 animated:YES];
     */
   
    //设置一个随机数
    for (int component=0; component         //获取当前列对应的数据元素的个数
        int total=[self.foods[component] count];
        //根据每一列的总数生成随机数（当前生成的随机数）
        int randomNumber=arc4random()%total;
       
        //获取当前选中的行（上一次随机后移动到的行）
        int oldRow=[self.pickerView selectedRowInComponent:0];
       
        //比较上一次的行号和当前生成的随机数是否相同，如果相同的话则重新生成
        while (oldRow==randomNumber) {
                randomNumber=arc4random()%total;
        }
       
        //让pickerview滚动到指定的某一行
        [self.pickerView selectRow:randomNumber inComponent:component animated:YES];
        //模拟，通过代码选中某一行
        [self pickerView:nil didSelectRow:randomNumber inComponent:component];
    }
}

#pragma mark- 设置数据
//一共多少列
-(NSInteger)numberOfComponentsInPickerView:(UIPickerView *)pickerView
{
    return self.foods.count;
}

//每列对应多少行
-(NSInteger)pickerView:(UIPickerView *)pickerView numberOfRowsInComponent:(NSInteger)component
{
    //1.获取当前的列
    NSArray *arayM= self.foods[component];
    //2.返回当前列对应的行数
    return arayM.count;
}

//每列每行对应显示的数据是什么
-(NSString *)pickerView:(UIPickerView *)pickerView titleForRow:(NSInteger)row forComponent:(NSInteger)component
{
    //1.获取当前的列
    NSArray *arayM= self.foods[component];
    //2.获取当前列对应的行的数据
    NSString *name=arayM[row];
    return name;
}

#pragma mark-设置下方的数据刷新
// 当选中了pickerView的某一行的时候调用
// 会将选中的列号和行号作为参数传入
// 只有通过手指选中某一行的时候才会调用
-(void)pickerView:(UIPickerView *)pickerView didSelectRow:(NSInteger)row inComponent:(NSInteger)component
{
    //获取对应列，对应行的数据
    NSString *name=self.foods[component][row];
    //赋值
    if (0==component) {
        self.fruitLab.text=name;
    }else if(1==component)
    {
        self.stapleLab.text=name;
    }else
        self.drinkLab.text=name;
}

#pragma mark-隐藏状态栏
-(BOOL)prefersStatusBarHidden
{
    return YES;
}
@end