無聊ing...封裝個省市區三級聯動選擇器的小demo吧。
上家公司的三級地區選擇器的數據是一次性通過網絡請求就能獲取到的，但新東家這邊并不是，而是先選擇了省獲取省的Id再去獲取市，再通過得到市的Id獲取區域，show code之前，先看下需要考慮的幾個點：
1）怎么設置默認值，關鍵代碼
[self.pickerView selectRow:xxx inComponent:xxx animated:YES];
2）怎么讓三級之間聯動 ,關鍵代碼
先看下效果圖
關于設置默認值，三級聯動，用UIPickView的話就是有3個輪子（component），首先我們要想到，第一次向后臺發起請求，我們只能獲取到第0個component的數據，只有當你滾動輪子的時候才會獲取到省的Id發起請求來獲得該省的市的數據，也就是第1個component的數據，依此類推，滾動第1個component發起請求來獲取第2個component的數據，因此，pickView的監聽輪子滾動的代理起了重要作用
我們通過接口獲取第0個component的數據，這邊是后臺規定的使用id=0，獲取到以后，默認選中第0個component的第0個row并主動調用觸發pick的輪子滾動代理來聯動第1個component【要在獲取數據成功后再執行這部操作,因此放在數據請求成功的回調內】，代碼為
[self pickerView:self.pickerView didSelectRow:0 inComponent:0 ];
在各輪子滾動過程中,用一個中間值
_selectedRow0記錄下第0個component的選中行
_selectedRow1記錄下第1個component的選中行
_selectedRow2記錄下第2個component的選中行，
這里需要記住，滾動某個輪子只能對它后面的輪子產生影響，所以當滾動第0個component的時候使_selectedRow1，_selectedRow2均置為0，這里注意，上面提到的
默認選中第0個component的第0個row并主動調用觸發pick的輪子滾動代理來聯動第1個component
要先將輪子上的數據渲染好，設置好默認值才能主動調用監聽輪子滾動的代理，否則會導致崩潰，另一個防崩潰的點如下圖
發現第三級沒數據的時候，如果你在代碼里沒加【安全措施】，那也會導致崩潰，要在請求到第三級的數據后做下判斷，如果個數為空，將該級對應的數據源置為nil。（其它兩級的輪子最好也加判斷）
最后，由于這是個封裝的類，最終要得到選中的詳細信息，可通過代理或block傳值給controller。
又是你們最喜歡show code環節：
.h文件
#import <UIKit/UIKit.h>//定制代理協議@protocol ZLMAddressPickerViewDelegate <NSObject>- (void)addressPickerViewDidSelected:(NSString *)areaName;//點擊上方完成按鈕的代理傳回拼接好的選中地址- (void)addressPickerViewDidClose;//點擊關閉代理@end@interface ZLMAddressPickerView : UIView@property (weak, nonatomic) id<ZLMAddressPickerViewDelegate> delegate;@end
.m文件
#import "ZLMAddressPickerView.h"#import "AFHttpUtils.h"#import "AreaModel.h"@interface ZLMAddressPickerView () <UIPickerViewDataSource, UIPickerViewDelegate>@property (strong, nonatomic) UIPickerView *pickerView;@property (strong, nonatomic) AreaModel *provBridge;@property (strong, nonatomic) AreaModel *cityBridge;@property (strong, nonatomic) AreaModel *areaBridge;@property (copy, nonatomic) NSArray<Area *> * provDataArr;//省數組@property (copy, nonatomic) NSArray<Area *> * cityDataArr;//市數組@property (copy, nonatomic) NSArray<Area *> * areaDataArr;//區數組@end@implementation ZLMAddressPickerView{ NSInteger _selectRow0;//記錄第0個輪子的選擇行 NSInteger _selectRow1; NSInteger _selectRow2; NSString *_areaString;//最后要傳回的詳細地址拼接字符串 Area *_proModel;//記錄下選中省的數據 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:@"關閉" 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 ];//聯動輪子1 必須得本輪有數據后才能觸發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];//默認選擇row0 [self pickerView:self.pickerView didSelectRow:0 inComponent:1 ];//聯動輪子2 必須得本輪有數據后才能觸發didselect _cityModel = self.cityDataArr[_selectRow1]; [self downloadAreaWithId:_cityModel.area_id]; } } errorHandle:^(NSError *error) { }]; }/*區*/- (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//確定picker的輪子個數- (NSInteger)numberOfComponentsInPickerView:(UIPickerView *)pickerView { return 3;}//確定picker的每個輪子的item數- (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;}//確定每個輪子的每一項顯示什么內容- (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;}//監聽輪子的移動- (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中調用
（1）導入
#import "ZLMAddressPickerView.h"
（2）定義一個對象并遵守代理協議
@property (strong, nonatomic) ZLMAddressPickerView *addressPickerView;
(3)懶加載生成對象（個人習慣）
- (ZLMAddressPickerView *)addressPickerView { if (!_addressPickerView) { _addressPickerView = [[ZLMAddressPickerView alloc] initWithFrame:CGRectMake(0, SCREEN_HEIGHT-244-64, SCREEN_WIDTH, 244)]; _addressPickerView.delegate = self; } return _addressPickerView;}（4）在點擊跳出三級聯動選擇器的地方
[self.view addSubview:self.addressPickerView];
(5)別忘了實現代理
#pragma mark - ZLMAddressPickerViewDelegate- (void)addressPickerViewDidSelected:(NSString *)areaName { self.areaLabel.text = areaName;//將傳回的詳細地址字符串賦值 [self addressPickerViewDidClose];}- (void)addressPickerViewDidClose { [self.addressPickerView removeFromSuperview];}以上就是本文的全部內容，希望對大家的學習有所幫助，也希望大家多多支持武林網。
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