207，省市联动效果

JSProvince.h:

#import <Foundation/Foundation.h>

@interface JSProvince : NSObject

@property(nonatomic,copy)NSString *name;

@property(nonatomic,copy)NSArray *cities;

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

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

@end

JSProvince.m:

#import "JSProvince.h"

@implementation JSProvince

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

    

    if (self = [superinit]) {

        [selfsetValuesForKeysWithDictionary:dict];

    }

    

    return self;

}

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

    return  [[selfalloc] initWithDict:dict];

}

@end

JSViewController.m:

#import "JSViewController.h"

#import "JSProvince.h"

@interface JSViewController ()<UIPickerViewDataSource,UIPickerViewDelegate>

@property(nonatomic,strong)NSArray *provinces;

@property (weak, nonatomic) IBOutletUIPickerView *pickerView;

@property (nonatomic,assign)int provinceIndex;//省份选中索引

@end

@implementation JSViewController

-(NSArray *)provinces{

    if (_provinces ==nil) {

              NSMutableArray *provincesTmp = [NSMutableArrayarray];

        NSString *path = [[NSBundlemainBundle] pathForResource:@"provinces"ofType:@"plist"];

        NSArray *data = [NSArrayarrayWithContentsOfFile:path];

        for (NSDictionary *dictin data) {

            JSProvince *province = [JSProvinceprovinceWithDict:dict];

            [provincesTmp addObject:province];

        }

        

        _provinces = provincesTmp;

    }

    

    return_provinces;

}

- (void)viewDidLoad

{

    [superviewDidLoad];

    NSLog(@"%@",self.provinces);

}

//两组

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

    return 2;

}

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

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

    //第一组

    if (component == 0) {

        return self.provinces.count;

    }else{

    //第二组

        JSProvince *province = self.provinces[_provinceIndex];

        return province.cities.count;

    }

}

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

    if (component == 0) {

        return 100;

    }else{

        return 80;

    }

}

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

    UILabel *label = nil;

    if (view == nil) {

        label =[[UILabel alloc] init];

    }else{

        label = (UILabel *)view;

    }

    

    if (component == 0) {

        JSProvince *province = self.provinces[row];

        label.text = province.name;

        label.backgroundColor = [UIColoryellowColor];

    }else{

        JSProvince *province = self.provinces[_provinceIndex];

        label.text = province.cities[row];

        label.backgroundColor = [UIColorgrayColor];

    }

    

    return label;

}

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

    if (component == 0) {

        _provinceIndex = row;

        [pickerView reloadComponent:1];

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

    }

}

@end