.網絡請求數據

首先你得有個天氣的API，API最好要求返回的JSON數據比較規范便于數據轉模型，由于只是初學只是練手所以無需找那些付費的API。

在這里我是使用百度的API：http://apistore.baidu.com/apiworks/servicedetail/112.html

其他天氣API可以自行百度。

找到API之后進行網絡請求并且解析從服務器返回的天氣數據。

在iOS9之后NSURLConnection被蘋果棄用而推薦使用NSURLSession,所以我這里使用NSURLSession。

-(void)requestCityWeather{

 NSString *cityName = @"城市名"; 
 NSString *cityID = @"城市ID"； 
 //這個是API地址 
 NSString *httpUrl = @"http://apis.baidu.com/apistore/weatherservice/recentweathers"; 
 NSString *utf8 = [cityName stringByAddingPercentEncodingWithAllowedCharacters:[NSCharacterSet URLQueryAllowedCharacterSet]]; 
 NSString *httpArg = [NSString stringWithFormat:@"cityname=%@&cityid=%@",utf8,cityID]; 
 [self request:httpUrl withHttpArg:httpArg];
}
//獲取數據
-(void)request: (NSString*)httpUrl withHttpArg: (NSString*)HttpArg { 
 NSString *urlStr = [[NSString alloc]initWithFormat: @"%@?%@", httpUrl, HttpArg]; 
 NSURL *url = [NSURL URLWithString: urlStr]; 

 //1.創建一個request
 NSMutableURLRequest *request = [[NSMutableURLRequest alloc]initWithURL: url cachePolicy:NSURLRequestUseProtocolCachePolicy timeoutInterval: 10]; 
 [request setHTTPMethod: @"GET"]; 
 [request addValue: @"您自己的apikey" forHTTPHeaderField: @"apikey"]; 
 
 //2.進行網絡請求 
 NSURLSession *session = [NSURLSession sharedSession]; 
 NSURLSessionDataTask *task = [session dataTaskWithRequest:request completionHandler:^(NSData * _Nullable data, NSURLResponse * _Nullable response, NSError * _Nullable error) { //當請求完成后執行這個block 請求下來的數據會在一個NSData里 if (error) { NSLog(@"Httperror: %@%ld", error.localizedDescription, error.code); } else { NSInteger responseCode = [(NSHTTPURLResponse *)response statusCode]; NSString *responseString = [[NSString alloc] initWithData:data encoding:NSUTF8StringEncoding]; NSLog(@"HttpResponseCode:%ld", responseCode); NSLog(@"HttpResponseBody %@",responseString); //把JSON數據轉成字典 NSDictionary *dataDict = [NSJSONSerialization JSONObjectWithData:data options:NSJSONReadingMutableLeaves error:nil]; NSDictionary *dataDic = [dataDict objectForKey:@"retData"]; NSLog(@"dataDic - %@",self.weatherDic); } }]; [task resume]; //不能漏}

這時候天氣數據就在一個字典中了，那么第一步也就完成了。

2.字典轉模型

這時候你的數據在一個字典里，這時候需要字典轉模型。

若有不明白字典轉模型的可以看這篇文章：http://www.cnblogs.com/wendingding/p/3749530.html

也可以自行百度。

這個是百度API返回的實例

從返回的JSON數據來看需要嵌套模型，過濾掉不需要的信息。

創建如上類

WeatherData.h

WeatherData.m

TodayData.h

TodayData.m??

#import "TodayData.h"

@implementation TodayData

-(instancetype)initWithDic:(NSDictionary *)dic{
 self = [super init]; 
 if (self) {
 NSString *str = [dic[@"curTemp"] substringWithRange:NSMakeRange(0, [dic[@"curTemp"] length] - 1)]; 
 str = [str stringByAppendingString:@"°"]; 
 self.curTemp = str; 
 self.date = dic[@"date"]; 
 self.fengli = dic[@"fengli"]; 
 self.fengxiang = dic[@"fengxiang"]; 
 self.highTemp = dic[@"hightemp"]; 
 self.lowTemp = dic[@"lowtemp"]; 
 self.pm = dic[@"aqi"]; 
 self.week = dic[@"week"]; 
 self.type = dic[@"type"]; 
 self.time = dic[@"time"]; 
 self.api = [self getAirPollutionIndex]; 
 self.index = [TodayIndex initWithDic:dic[@"index"]]; 
 } 
 return self;
}

+(instancetype)initWithDic:(NSDictionary *)dic{
 return [[self alloc]initWithDic:dic];
}

-(NSString *)getAirPollutionIndex{
 NSLog(@"api: - %@",self.pm); 
 if ((NSNull *)self.pm == [NSNull null]){
 return @"無數據"; 
 }else if (self.pm.intValue <= 50) {
 return @"優"; 
 }else if (self.pm.intValue <= 100 && self.pm.intValue > 50){
 return @"良"; 
 }else if (self.pm.intValue <= 150 && self.pm.intValue > 100){
 return @"輕度污染"; 
 }else if (self.pm.intValue <= 200 && self.pm.intValue > 150){
 return @"中度污染"; 
 }else if (self.pm.intValue <= 300 && self.pm.intValue > 200){
 return @"重度污染"; 
 }else{
 return @"嚴重污染"; 
 }
}
@end

其他模型類都是差不多的。

寫好模型數據之后 數據部分就完成了。

文／SoolyChristina（簡書作者）