iOS - UIPickView

1,代理

//UIPickView和TableView一样,想要展示数据也要设置数据源和代理

// 设置数据源
 self.pickView.dataSource = self;
// 设置代理
 self.pickView.delegate = self;


//遵守数据源,代理协议:

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


//实现数据源代理方法:

//总共有多少列
- (NSInteger)numberOfComponentsInPickerView:(UIPickerView *)pickerView{
    return 3;
}

//第component列有多少行.
- (NSInteger)pickerView:(UIPickerView *)pickerView numberOfRowsInComponent:(NSInteger)component{
    return 4;
}
//返回每一列的宽度
- (CGFloat)pickerView:(UIPickerView *)pickerView widthForComponent:(NSInteger)component{
}
//返回第一列的高度
- (CGFloat)pickerView:(UIPickerView *)pickerView rowHeightForComponent:(NSInteger)component{
    return 50;
}

//返回每一行的标题
- (nullable NSString *)pickerView:(UIPickerView *)pickerView titleForRow:(NSInteger)row forComponent:(NSInteger)component{
    return @"gaowei";
}


//返回每一行的视图UIView
- (UIView *)pickerView:(UIPickerView *)pickerView viewForRow:(NSInteger)row forComponent:(NSInteger)component reusingView:(nullable UIView *)view{

    UIButton *btn = [UIButton buttonWithType:UIButtonTypeContactAdd];
    return btn;
}

2,简单Demo

image.png

#import "ViewController.h"

@interface ViewController ()

//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;

}