请问 怎么 利用天气预报接口根据城市名得到城市代码？

先把代码表存储到一个plist文件中

然后：

`NSString *plistPath = [[NSBundle mainBundle] pathForResource:@"cityList" ofType:@"plist"];
_areaidDictionary = [[NSDictionary alloc] initWithContentsOfFile:plistPath];`
areaidDictionary是区域id的字典

之后用

- (void)transToareaidfromLocation:(CLLocation *)location {
    self.areaid = nil;
    self.geocoder = [[CLGeocoder alloc] init];
    [self.geocoder reverseGeocodeLocation:location
    completionHandler:^(NSArray *placemarks, NSError *error) {
        if (error == nil && [placemarks count] > 0) {
            CLPlacemark *placemark = [placemarks objectAtIndex:0];
            self.city = placemark.locality;
            self.areaid = self.areaidDictionary[self.city];
            NSLog(@"city:%@",self.city);
            NSLog(@"areaid:%@",self.areaid);
        } else if (error == nil && [placemarks count] == 0) {
            NSLog(@"No location results were returned");
        } else if (error != nil) {
            NSLog(@"An error occurred:%@",error.description);
        }
    }];
}

在反地理编码的同时，利用字典找到areaid。
areaid就是你要的城市代码。