#import "ViewController.h"

@interface ViewController ()<UIPickerViewDataSource,UIPickerViewDelegate>

展示数据的pickView

@property (weak, nonatomic) IBOutlet UIPickerView *pickView;

 

数组当中有3个小数组, 每一个小数组代表一列.每一列小数组的个数代表这一列有多少行.

@property(nonatomic,strong) NSArray *foodArray;

显示当前选中的食物

@property (weak, nonatomic) IBOutlet UILabel *foodLabel;

@end

@implementation ViewController

 

 

 

 

 

 

懒加载数据

-(NSArray *)foodArray{

   

    if (_foodArray == nil) {

        获取Plist文件的路径

        NSString *filePath = [[NSBundle mainBundle] pathForResource:@"foods.plist" ofType:nil];

        从Plist文件当中加载数组.

        _foodArray = [NSArray arrayWithContentsOfFile:filePath];

       

    }

    return _foodArray;

}

- (void)viewDidLoad {

    [super viewDidLoad];

    设置数据源

    self.pickView.dataSource = self;

    设置代理

    self.pickView.delegate = self;

}

 

 

总共有多少列

- (NSInteger)numberOfComponentsInPickerView:(UIPickerView *)pickerView{

     数组当中有几个元素, 就展示多少列.每一个元素代表一列,

    return self.foodArray.count;

}

 

第component列有多少行.

- (NSInteger)pickerView:(UIPickerView *)pickerView numberOfRowsInComponent:(NSInteger)component{

    取出当前所在的列.每一列都是一个数组.

    NSArray *array = self.foodArray[component];

    返回每一组当中, 每一个小数组的数个, 也就是这一组里面有多少行.

    return array.count;

}

 

返回每一行的标题

- (nullable NSString *)pickerView:(UIPickerView *)pickerView titleForRow:(NSInteger)row forComponent:(NSInteger)component{

    取出当前所在的列.每一列都是一个数组.

    NSArray *componentArray = self.foodArray[component];

    返回小数组当中每一个元素

    return componentArray[row];

}

 

点击了哪一列的哪一行

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

    NSString *food = self.foodArray[component][row];

    self.foodLabel.text = food;

}