UIPickerView的属性和常用方法 举例：显示省份和城市

#import "ViewController.h"

@interface ViewController ()

@property(strong, nonatomic) UIPickerView * pickerView;
@property(strong, nonatomic) UILabel * label;
@property(strong, nonatomic) UIButton * button;
@property (nonatomic, strong)  NSDictionary  *pickerData; //保存全部数据
@property (nonatomic, strong)  NSArray  *pickerProvincesData;//当前的省数据
@property (nonatomic, strong)  NSArray  *pickerCitiesData;//当前的省下面的市数据

@end

@implementation ViewController

- (void)viewDidLoad {
    [super viewDidLoad];
    // Do any additional setup after loading the view, typically from a nib.
    
    self.pickerView = [[UIPickerView alloc]initWithFrame:CGRectMake(0, 48, 320, 162)];
    self.pickerView.backgroundColor = [UIColor groupTableViewBackgroundColor];
    [self.view addSubview:self.pickerView];
    self.label = [[UILabel alloc]initWithFrame:CGRectMake(63, 285, 195, 33)];
    self.label.textAlignment = NSTextAlignmentCenter;
    self.label.text = @"显示信息";
    self.label.backgroundColor = [UIColor groupTableViewBackgroundColor];
    [self.view addSubview:self.label];
    self.button = [[UIButton alloc]initWithFrame:CGRectMake(88, 413, 144, 44)];
    [self.button setTitle:@"显示在Label上" forState:UIControlStateNormal];
    self.button.backgroundColor = [UIColor brownColor];
    [self.button addTarget:self action:@selector(tapShow) forControlEvents:UIControlEventTouchUpInside];
    [self.view addSubview:self.button];
    
    NSString *plistPath = [[NSBundle mainBundle] pathForResource:@"PC" ofType:@"plist"];
    //获取属性列表文件中的全部数据
    NSDictionary *dict = [[NSDictionary alloc] initWithContentsOfFile:plistPath];
    self.pickerData = dict;
    
    //省份名数据
    self.pickerProvincesData =  [self.pickerData allKeys];
    
    //默认取出第一个省的所有市的数据
    NSString *seletedProvince = [self.pickerProvincesData objectAtIndex:0];
    self.pickerCitiesData = [self.pickerData objectForKey:seletedProvince];
    
    self.pickerView.dataSource = self;
    self.pickerView.delegate = self;
    
    
}

- (void)tapShow
{
    NSInteger row1 = [self.pickerView selectedRowInComponent:0];
    NSInteger row2 = [self.pickerView selectedRowInComponent:1];
    //NSLog(@"row1 = %lu",row1);
    //NSLog(@"row2 = %lu",row2);
    NSString *selected1 = [self.pickerProvincesData objectAtIndex:row1];
    NSString *selected2 = [self.pickerCitiesData objectAtIndex:row2];
    
    NSString *title = [[NSString alloc] initWithFormat:@"%@，%@",
                       selected1,selected2];
    
    self.label.text = title;
    
}

#pragma mark 实现协议UIPickerViewDataSource方法
- (NSInteger)numberOfComponentsInPickerView:(UIPickerView *)pickerView {
    return 2;
}
//初始化时component先为0，后为1，返回省份个数和和市的个数，以确定省份的行数和市的临时初始化行数。此后选择省的时候component为1，返回市的个数
- (NSInteger)pickerView:(UIPickerView *)pickerView
numberOfRowsInComponent:(NSInteger)component {
    if (component == 0)
    {//省份个数
        return [self.pickerProvincesData count];
    } else
    {//市的个数
        return [self.pickerCitiesData count];
    }
    
}

#pragma mark 实现协议UIPickerViewDelegate方法
//选择省份的时候component先为0，后为1。然后选择市的时候返回市所在的row号。将其省和市显示在pickerview的显示条上
-(NSString *)pickerView:(UIPickerView *)pickerView
            titleForRow:(NSInteger)row forComponent:(NSInteger)component {
    //NSLog(@"row2 = %lu",row);
    //NSLog(@"component2 = %lu",component);
    if (component == 0)
    {//选择省份名
        return [self.pickerProvincesData objectAtIndex:row];
    } else
    {//选择市名
        return [self.pickerCitiesData objectAtIndex:row];
    }
}
//只有选择省份的时候component为0，返回省所在的row号，然后根据省份取出省所有的市。选择市的时候component为1。（作用为重新加载数据到pickerview上）
- (void)pickerView:(UIPickerView *)pickerView
      didSelectRow:(NSInteger)row inComponent:(NSInteger)component {
    //NSLog(@"row3 = %lu",row);
    //NSLog(@"component3 = %lu",component);
    if (component == 0)
    {
        NSString *seletedProvince = [self.pickerProvincesData objectAtIndex:row];
        NSArray *array = [self.pickerData objectForKey:seletedProvince];
        //NSLog(@"array = %@",array);
        self.pickerCitiesData = array;//将所选省的所有市存入pickerCitiesData
        [self.pickerView reloadComponent:1];
    }
}
- (void)didReceiveMemoryWarning {
    [super didReceiveMemoryWarning];
    // Dispose of any resources that can be recreated.
}

@end

1、常用属性

//显示选中框

showsSelectionIndicator

2、常用方法

//返回rows的所有行号行号

- (NSInteger)numberOfRowsInComponent:(NSInteger)component;

//重新加载所有的元素

- (void)reloadAllComponents;

//通过赋值加载所选择的数据

- (void)reloadComponent:(NSInteger)component;

//协议UIPickerViewDataSource方法

//确定轮子的列数

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

return 2;

}

//初始化时component先为0，后为1，返回省份个数和和市的个数，以确定省份的行数和市的临时初始化行数。此后选择省的时候component为1，返回市的个数

- (NSInteger)pickerView:(UIPickerView *)pickerView

numberOfRowsInComponent:(NSInteger)component {

if (component == 0)

{//省份个数

return [self.pickerProvincesData count];

} else

{//市的个数

return [self.pickerCitiesData count];

}

}

//协议UIPickerViewDelegate方法

//选择省份的时候component先为0，后为1。然后选择市的时候返回市所在的row号。将其省和市显示在pickerview的显示条上

-(NSString *)pickerView:(UIPickerView *)pickerView

titleForRow:(NSInteger)row forComponent:(NSInteger)component {

//NSLog(@"row2 = %lu",row);

//NSLog(@"component2 = %lu",component);

if (component == 0)

{//选择省份名

return [self.pickerProvincesData objectAtIndex:row];

} else

{//选择市名

return [self.pickerCitiesData objectAtIndex:row];

}

}

//只有选择省份的时候component为0，返回省所在的row号，然后根据省份取出省所有的市。选择市的时候component为1。（作用为重新加载数据到pickerview上）

- (void)pickerView:(UIPickerView *)pickerView

  didSelectRow:(NSInteger)row inComponent:(NSInteger)component {

//NSLog(@"row3 = %lu",row);

//NSLog(@"component3 = %lu",component);

if (component == 0)

{

NSString *seletedProvince = [self.pickerProvincesData objectAtIndex:row];

NSArray *array = [self.pickerData objectForKey:seletedProvince];

//NSLog(@"array = %@",array);

self.pickerCitiesData = array;//将所选省的所有市存入pickerCitiesData

[self.pickerView reloadComponent:1];

}

}