UIPickerView（省动联动 两列有关联)

"【案例: 省市联动】"

》添加Province模型加载plist文件

》实现PickerView的数据源和代理(用Main.storyboard)

(1)返回两组数据

(2)实现PickerView的代理，使用【-(UIView *)pickerView:viewForRow:forComponent:reusingView:】方法，返回一个Label

(3)添加一个当前省份选中索引IndexOfProv

(4)默认城市那一组数据 返回 第一个省份的城市数据

(5)当前省份选中的索引改变时，刷新城市数据并默认选中的第一个城市

*[pickerView reloadComponent:1];

*[pickerView selectRow:0 inComponent:1 animated:YES];

》掌握设置组宽的代理方法

(1)实现【-(CGFloat)pickerView:widthForComponent:】方法设置组的宽度

(2)设置两列View的背景颜色不同看出宽度的区别

Province.h

//

//  Province.h

//  03.省市联动

//

//  Created by Yong Feng Guo on 14-12-19.

//  Copyright (c) 2014年 Fung. All rights reserved.

//

 

#import <UIKit/UIKit.h>

 

@interface Province : NSObject

 

@property(nonatomic,copy)NSString *name;

@property(nonatomic,strong)NSArray *cities;

 

-(instancetype)initWithDict:(NSDictionary *)dict;

+(instancetype)provinceWithDict:(NSDictionary *)dict;

 

+(NSArray *)provinceList;

@end

Province.m 

//

//  Province.m

//  03.省市联动

//

//  Created by Yong Feng Guo on 14-12-19.

//  Copyright (c) 2014年 Fung. All rights reserved.

//

 

#import "Province.h"

 

@implementation Province

 

 

-(instancetype)initWithDict:(NSDictionary *)dict{

    if (self = [super init]) {

        [self setValuesForKeysWithDictionary:dict];

    }

    

    return self;

}

+(instancetype)provinceWithDict:(NSDictionary *)dict{

    return [[self alloc] initWithDict:dict];

}

 

+(NSArray *)provinceList

{

    //plist 文件路径

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

    NSArray *provincePlist = [NSArray arrayWithContentsOfFile:filePath];

    NSMutableArray *provinceM = [NSMutableArray array];

    for (NSDictionary *dic in provincePlist) {

        Province *prov = [Province provinceWithDict:dic];

        [provinceM addObject:prov];

        }

    

    return provinceM;

}

@end

ViewController.m

//

//  ViewController.m

//  03.省市联动

//

//  Created by huan on 16/1/8.

//  Copyright © 2016年 huanxi. All rights reserved.

//

 

#import "ViewController.h"

#import "Province.h"

@interface ViewController ()<UIPickerViewDataSource, UIPickerViewDelegate>

@property (nonatomic, strong) NSArray *provinces;

@property (nonatomic, assign) NSInteger indexOfProvince;//当前默认选中的省份

 

@end

 

@implementation ViewController

-(NSArray *)provinces

{

    if (!_provinces) {

        _provinces = [Province provinceList];

    }

    return _provinces;

}

- (void)viewDidLoad {

    [super viewDidLoad];

    // Do any additional setup after loading the view, typically from a nib.

    NSLog(@"%@", self.provinces);

}

 

// returns the number of 'columns' to display.

- (NSInteger)numberOfComponentsInPickerView:(UIPickerView *)pickerView

{

    return 2;

}

 

// returns the # of rows in each component..

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

{

//    return 12;

    if (component == 0) {

        return self.provinces.count;

    }

    //获得对应省份的城市的个数

    Province *province = self.provinces[self.indexOfProvince];

    return province.cities.count;

    

}

#pragma mark 显示数据

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

{

    //对应列行的省份

    Province *province = self.provinces[row];

    if (component == 0) {//显示省份的名字

        return province.name;

    }

    //获取选中的城市，显示城市的名字

    Province *selectedProvice = self.provinces[self.indexOfProvince];

    return selectedProvice.cities[row];

    

}

//-(UIView *)pickerView:(UIPickerView *)pickerView viewForRow:(NSInteger)row forComponent:(NSInteger)component reusingView:(UIView *)view{

//    UILabel *label = (UILabel *)view;

//    if (!label) {

//        label = [[UILabel alloc] init];

//    }

//    if (component == 0) {//显示省份的名字

//        

//        Province *province = self.provinces[row];

//        label.text = province.name;

//        label.backgroundColor = [UIColor grayColor];

//    }

//    else{

//    //获取选中的城市，显示城市的名字

//    Province *selectedProvice = self.provinces[self.indexOfProvince];

//    label.text = selectedProvice.cities[row];

//    label.backgroundColor = [UIColor blueColor];

//    }

//    return label;

//    

//}

 

 

 

#pragma mark 选中行

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

{

    if (component == 0) {//第一列省的选中改变后，就更新第二列数据

        

        //更新选中省份的索引

        self.indexOfProvince = row;

        //刷新数据

        //全部刷新

//        [pickerView reloadAllComponents];

        //部分刷新

        [pickerView reloadComponent:1];

        //不管之前第二列选中第几行，重新刷新数据后，都显示第二列的第一行

        [pickerView selectRow:0 inComponent:1 animated:YES];

    }

}

 

#pragma mark 设置宽度

-(CGFloat)pickerView:(UIPickerView *)pickerView widthForComponent:(NSInteger)component{

    if (component == 0) {

        return 80;

    }

    return 200;

}

 

 

- (void)didReceiveMemoryWarning {

    [super didReceiveMemoryWarning];

    // Dispose of any resources that can be recreated.

}

 

@end