本篇文章为大家展示了怎么在iOS中实现一个三级联动选择器，内容简明扼要并且容易理解，绝对能使你眼前一亮，通过这篇文章的详细介绍希望你能有所收获。
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1）怎么设置默认值，关键代码
[self.pickerView selectRow:xxx inComponent:xxx animated:YES];
2）怎么让三级之间联动 ,关键代码
[self pickerView:self.pickerView didSelectRow:0 inComponent:0 ];//联动轮子1 必须得本轮有数据后触发否则crash
先看下效果图
关于设置默认值，三级联动，用UIPickView的话就是有3个轮子（component），首先我们要想到，第一次向后台发起请求，我们只能获取到第0个component的数据，只有当你滚动轮子的时候才会获取到省的Id发起请求来获得该省的市的数据，也就是第1个component的数据，依此类推，滚动第1个component发起请求来获取第2个component的数据，因此，pickView的监听轮子滚动的代理起了重要作用
- (void)pickerView:(UIPickerView *)pickerView didSelectRow:(NSInteger)row inComponent:(NSInteger)component；
我们通过接口获取第0个component的数据，这边是后台规定的使用id=0，获取到以后，默认选中第0个component的第0个row并主动调用触发pick的轮子滚动代理来联动第1个component【要在获取数据成功后再执行这部操作,因此放在数据请求成功的回调内】，代码为
[self pickerView:self.pickerView didSelectRow:0 inComponent:0 ];
在各轮子滚动过程中,用一个中间值
_selectedRow0记录下第0个component的选中行
_selectedRow1记录下第1个component的选中行
_selectedRow2记录下第2个component的选中行，
这里需要记住，滚动某个轮子只能对它后面的轮子产生影响，所以当滚动第0个component的时候使_selectedRow1，_selectedRow2均置为0，这里注意，上面提到的
默认选中第0个component的第0个row并主动调用触发pick的轮子滚动代理来联动第1个component
要先将轮子上的数据渲染好，设置好默认值才能主动调用监听轮子滚动的代理，否则会导致崩溃，另一个防崩溃的点如下图
发现第三级没数据的时候，如果你在代码里没加【安全措施】，那也会导致崩溃，要在请求到第三级的数据后做下判断，如果个数为空，将该级对应的数据源置为nil。（其它两级的轮子最好也加判断）
最后，由于这是个封装的类，最终要得到选中的详细信息，可通过代理或block传值给controller。
又是你们最喜欢show code环节：
.h文件
#import
//定制代理协议
@protocol ZLMAddressPickerViewDelegate
- (void)addressPickerViewDidSelected:(NSString *)areaName;//点击上方完成按钮的代理传回拼接好的选中地址
- (void)addressPickerViewDidClose;//点击关闭代理
@end
@interface ZLMAddressPickerView : UIView
@property (weak, nonatomic) id delegate;
@end
.m文件
#import "ZLMAddressPickerView.h"
#import "AFHttpUtils.h"
#import "AreaModel.h"
@interface ZLMAddressPickerView ()
@property (strong, nonatomic) UIPickerView *pickerView;
@property (strong, nonatomic) AreaModel *provBridge;
@property (strong, nonatomic) AreaModel *cityBridge;
@property (strong, nonatomic) AreaModel *areaBridge;
@property (copy, nonatomic) NSArray * provDataArr;//省数组
@property (copy, nonatomic) NSArray * cityDataArr;//市数组
@property (copy, nonatomic) NSArray * areaDataArr;//区数组
@end
@implementation ZLMAddressPickerView
{
NSInteger _selectRow0;//记录第0个轮子的选择行
NSInteger _selectRow1;
NSInteger _selectRow2;
NSString *_areaString;//最后要传回的详细地址拼接字符串
Area *_proModel;//记录下选中省的数据
Area *_cityModel;
Area *_areaModel;
}
- (instancetype)initWithFrame:(CGRect)frame
{
self = [super initWithFrame:frame];
if (self) {
[self setup];
}
return self;
}
- (void)setup {
_selectRow0 = 0;
_selectRow1 = 0;
_selectRow2 = 0;
self.backgroundColor = [UIColor whiteColor];
UIToolbar *toolbar = [[UIToolbar alloc] initWithFrame:CGRectMake(0, 0, CGRectGetWidth(self.bounds), 44)];
toolbar.backgroundColor = [UIColor whiteColor];
[self addSubview:toolbar];
UIBarButtonItem *closeItem = [[UIBarButtonItem alloc] initWithTitle:@"关闭" style:UIBarButtonItemStylePlain target:self action:@selector(selectAddressClose)];
UIBarButtonItem *completeItem = [[UIBarButtonItem alloc] initWithTitle:@"完成" style:UIBarButtonItemStylePlain target:self action:@selector(selectAddressComplete)];
UIBarButtonItem *spaceItem = [[UIBarButtonItem alloc] initWithBarButtonSystemItem:UIBarButtonSystemItemFlexibleSpace target:nil action:nil];
toolbar.items = @[closeItem, spaceItem, completeItem];
self.pickerView.frame = CGRectMake(0, 44, CGRectGetWidth(self.bounds), CGRectGetHeight(self.bounds) - 44);
[self addSubview:self.pickerView];
[self downloadProv];
}
#pragma mark - http methods
/*省*/
- (void)downloadProv {
NSMutableDictionary *dic = [NSMutableDictionary dictionaryWithDictionary: @{@"id":@(0)} ];
[AFHttpUtils sendPostTaskWithUrl:[NSString stringWithFormat:@"%@/app/member/area",BASE_DOMAIN_URL] paramenters:dic successHandle:^(NSURLSessionDataTask *task, id responseObject) {
NSLog(@"PROV:%@",responseObject);
self.provBridge = [AreaModel mj_objectWithKeyValues:responseObject];
if (self.provBridge.error_code==0) {
self.provDataArr=self.provBridge.data;
[self pickerView:self.pickerView didSelectRow:0 inComponent:0 ];//联动轮子1 必须得本轮有数据后才能触发didselect
[self.pickerView reloadAllComponents];
}
} errorHandle:^(NSError *error) {
}];
}
/*市*/
- (void)downloadCityWithId:(NSInteger)provId {
NSMutableDictionary *dic = [NSMutableDictionary dictionaryWithDictionary: @{@"id":@(provId)} ];
[AFHttpUtils sendPostTaskWithUrl:[NSString stringWithFormat:@"%@/app/member/area",BASE_DOMAIN_URL] paramenters:dic successHandle:^(NSURLSessionDataTask *task, id responseObject) {
NSLog(@"CITY:%@",responseObject);
self.cityBridge = [AreaModel mj_objectWithKeyValues:responseObject];
if (self.cityBridge.error_code==0) {
self.cityDataArr=self.cityBridge.data;
[self.pickerView reloadComponent:1];
[self.pickerView selectRow:0 inComponent:1 animated:YES];//默认选择row0
[self pickerView:self.pickerView didSelectRow:0 inComponent:1 ];//联动轮子2 必须得本轮有数据后才能触发didselect
_cityModel = self.cityDataArr[_selectRow1];
[self downloadAreaWithId:_cityModel.area_id];
}
} errorHandle:^(NSError *error) {
}];
}
/*区*/
- (void)downloadAreaWithId:(NSInteger)cityId {
NSMutableDictionary *dic = [NSMutableDictionary dictionaryWithDictionary: @{@"id":@(cityId)} ];
[AFHttpUtils sendPostTaskWithUrl:[NSString stringWithFormat:@"%@/app/member/area",BASE_DOMAIN_URL] paramenters:dic successHandle:^(NSURLSessionDataTask *task, id responseObject) {
NSLog(@"AREA:%@",responseObject);
self.areaBridge = [AreaModel mj_objectWithKeyValues:responseObject];
if (self.areaBridge.error_code==0&&self.areaBridge.data.count>0) {
self.areaDataArr=self.areaBridge.data;
}else{
self.areaDataArr=nil;
}
[self.pickerView reloadComponent:2];
[self.pickerView selectRow:0 inComponent:2 animated:YES];
[self pickerView:self.pickerView didSelectRow:0 inComponent:2 ];
} errorHandle:^(NSError *error) {
}];
}
#pragma mark - events response
- (void)selectAddressComplete {
[self.delegate addressPickerViewDidSelected:_areaString];
}
- (void)selectAddressClose {
[self.delegate addressPickerViewDidClose];
}
#pragma mark - UIPickerViewDataSource
//确定picker的轮子个数
- (NSInteger)numberOfComponentsInPickerView:(UIPickerView *)pickerView {
return 3;
}
//确定picker的每个轮子的item数
- (NSInteger)pickerView:(UIPickerView *)pickerView numberOfRowsInComponent:(NSInteger)component {
if (component==0) {
return self.provDataArr.count;
}else if(component==1){
return self.cityDataArr.count;
}else{
return self.areaDataArr.count;
}
}
- (CGFloat)pickerView:(UIPickerView *)pickerView rowHeightForComponent:(NSInteger)component{
return 36;
}
//确定每个轮子的每一项显示什么内容
- (NSAttributedString *)pickerView:(UIPickerView *)pickerView attributedTitleForRow:(NSInteger)row forComponent:(NSInteger)component{
NSDictionary * attrDic = @{NSForegroundColorAttributeName:[UIColor blackColor],
NSFontAttributeName:[UIFont systemFontOfSize:12]};
Area *area;
if (component==0) {
area = self.provDataArr[row];
}else if(component==1){
area = self.cityDataArr[row];
}else{
area = self.areaDataArr[row];
}
NSAttributedString * attrString = [[NSAttributedString alloc] initWithString:area.name
attributes:attrDic];
return attrString;
}
//监听轮子的移动
- (void)pickerView:(UIPickerView *)pickerView didSelectRow:(NSInteger)row inComponent:(NSInteger)component {
if (component==0) {
_selectRow0 = [pickerView selectedRowInComponent:0];
_selectRow1 = 0;
_selectRow2 = 0;
_proModel = self.provDataArr[_selectRow0];
[self downloadCityWithId:_proModel.area_id];
}else if(component==1){
_selectRow1 = [pickerView selectedRowInComponent:1];
_selectRow2 = 0;
_cityModel = self.cityDataArr[_selectRow1];
[self downloadAreaWithId:_cityModel.area_id];
}else{
_selectRow2 = [pickerView selectedRowInComponent:2];
if (self.areaDataArr&&self.areaDataArr.count>0) {
_areaModel = self.areaDataArr[_selectRow2];
}else{
_areaModel = nil;
}
}
if(_areaModel==nil){
_areaString = [NSString stringWithFormat:@"%@ %@",_proModel.name,_cityModel.name];
}else{
_areaString = [NSString stringWithFormat:@"%@ %@ %@",_proModel.name,_cityModel.name,_areaModel.name];
}
}
#pragma mark - getters and setters
- (UIPickerView *)pickerView {
if (_pickerView == nil) {
_pickerView = [[UIPickerView alloc] init];
_pickerView.delegate = self;
_pickerView.dataSource = self;
}
return _pickerView;
}
@end
最后在controller中调用
（1）导入
#import "ZLMAddressPickerView.h"
（2）定义一个对象并遵守代理协议
@property (strong, nonatomic) ZLMAddressPickerView *addressPickerView;
(3)懒加载生成对象（个人习惯）
- (ZLMAddressPickerView *)addressPickerView {
if (!_addressPickerView) {
_addressPickerView = [[ZLMAddressPickerView alloc] initWithFrame:CGRectMake(0, SCREEN_HEIGHT-244-64, SCREEN_WIDTH, 244)];
_addressPickerView.delegate = self;
}
return _addressPickerView;
}（4）在点击跳出三级联动选择器的地方
[self.view addSubview:self.addressPickerView];
(5)别忘了实现代理
#pragma mark - ZLMAddressPickerViewDelegate
- (void)addressPickerViewDidSelected:(NSString *)areaName {
self.areaLabel.text = areaName;//将传回的详细地址字符串赋值
[self addressPickerViewDidClose];
}
- (void)addressPickerViewDidClose {
[self.addressPickerView removeFromSuperview];
}上述内容就是怎么在iOS中实现一个三级联动选择器，你们学到知识或技能了吗？如果还想学到更多技能或者丰富自己的知识储备，欢迎关注创新互联行业资讯频道。
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