iOS pickerView

#import "ViewController.h"

@interface ViewController ()<UIPickerViewDataSource,UIPickerViewDelegate>
@property (nonatomic,strong)NSArray *foods;
//显示水果
@property (weak, nonatomic) IBOutlet UILabel *fruitLabel;
//显示主食
@property (weak, nonatomic) IBOutlet UILabel *mainLabel;
//显示饮料
@property (weak, nonatomic) IBOutlet UILabel *drinkLable;
@property (weak, nonatomic) IBOutlet UIPickerView *pickerView;
//随机
- (IBAction)radom:(id)sender;
//确认
- (IBAction)certain:(id)sender;
//取消
- (IBAction)cancel:(id)sender;

@end

@implementation ViewController

//懒加载数组
-(NSArray *)foods{
    if (_foods==nil) {
        _foods=[NSArray arrayWithContentsOfFile:[[NSBundle mainBundle]pathForResource:@"foods" ofType:@"plist"]];
    }
    return _foods;
}
- (void)viewDidLoad {
    [super viewDidLoad];
    // Do any additional setup after loading the view.
    for (int i=0; i<3; i++) {
        [self pickerView:nil didSelectRow:0 inComponent:i];
    }
}

//总共多少列
-(NSInteger)numberOfComponentsInPickerView:(UIPickerView *)pickerView{
    return self.foods.count;
}

//总共多少行
-(NSInteger)pickerView:(UIPickerView *)pickerView numberOfRowsInComponent:(NSInteger)component{
    NSArray *subFood=self.foods[component];
    return subFood.count;
}

//第component列第row行显示文字内容
-(NSString *)pickerView:(UIPickerView *)pickerView titleForRow:(NSInteger)row forComponent:(NSInteger)component{
    return self.foods[component][row];
}

//选中第component列第row行
-(void)pickerView:(UIPickerView *)pickerView didSelectRow:(NSInteger)row inComponent:(NSInteger)component{
    //选中行的文本显示对应的Label
    if(component==0){
        self.fruitLabel.text=self.foods[component][row];
    }else if(component==1){
        self.mainLabel.text=self.foods[component][row];
    }else if(component==2){
        self.drinkLable.text=self.foods[component][row];
    }
}

//设置行高
-(CGFloat)pickerView:(UIPickerView *)pickerView rowHeightForComponent:(NSInteger)component{
    return 35;
}

//随机一份套餐
- (IBAction)radom:(id)sender {
    for (int component=0;component<self.foods.count;component++){
        //第compnent列数组的总长度
        int count=(int)[self.foods[component]count];
        //旧的行号
        int oldRow=(int)[self.pickerView selectedRowInComponent:component];
        //第几行，默认旧行号与新行号相同
        int row=oldRow;
        //保证行号与上次不一样
        while(row==oldRow){
            row=arc4random()%count;
        }
        //让pickerView主动选中第compoent列的第row行
        [self.pickerView selectRow:row inComponent:component animated:YES];
        //设置label的文字
        [self pickerView:nil didSelectRow:row inComponent:component];
    }
}

- (IBAction)certain:(id)sender {
    //提示用户点餐成功
    UIAlertController *alertC=[UIAlertController alertControllerWithTitle:@"点餐成功" message:@"请稍后..." preferredStyle:UIAlertControllerStyleAlert];
    UIAlertAction *certain=[UIAlertAction actionWithTitle:@"好的" style:UIAlertActionStyleDefault handler:nil];
    [alertC addAction:certain];
    [self presentViewController:alertC animated:YES completion:nil];
}

- (IBAction)cancel:(id)sender {
    //直接初始化
    for(int i=0;i<3;i++){
        [self pickerView:nil didSelectRow:0 inComponent:i];
        [self.pickerView selectRow:0 inComponent:i animated:YES];
    }
}
@end