使用Json时currentCenter返回nil iOS

Question

The JSON Data

Please HELP I beg

  2015-10-30 12:15:58.866 GooglePlaces[17141:989254] Google Data: (
    {
        geometry =         {
            location =             {
                lat = "55.599881";
                lng = "-2.64616";
            };
        };
        icon = "https://maps.gstatic.com/mapfiles/place_api/icons/generic_business-71.png";
        id = 4e3047fc80549f89389827d05fb89a999705fcf2;
        name = "Scott's view";
        photos =         (
                        {
                height = 2368;
                "html_attributions" =                 (
                    "<a href=\"https://maps.google.com/maps/contrib/113818044483598102211\">Clarke Thomas</a>"
                );
                "photo_reference" = "CmRdAAAADgCHDAr9O_RZg24-kHykYexBOTpKfhOAWTV-K1Go-sn6CGUoikhGc3beyjErYvXzCPLwFLRr32lC8tPpgfIA-CXue6l75ziHrlRXMOt72IZFBcbZfCBSSbttW5lHjSdfEhD5d08GC5Myl8L1_Zs0VmW2GhTzCD7bh_klEqsROxGDZLvskhzaBw";
                width = 3200;
            }
        );
        "place_id" = ChIJP5eCRF54h0gR9nc97bjfO8k;
        rating = "4.7";
        reference = "CmRgAAAAfN6yeOvYQEeRAzOcidZiE83kPoIdw_vDDH7orFr3gbZVXHeb3prAMlOCVWnVqeeK786c8x-V1QUtWfpSn-50Bk4Q5lO7fY04cNLsXigf1nx1JWiTee5d4TdKI1ij-jGDEhDXYtJPM_1H5t9KhqdSJiyuGhQAXqV2rosfllEOfE-suQ_ur89Bmg";
        scope = GOOGLE;
        types =         (
            parking,
            "point_of_interest",
            establishment
        );
        vicinity = B6356;
    },
        {
        geometry =         {
            location =             {
                lat = "55.756977";
                lng = "-4.17221";
            };
        };
        icon = "https://maps.gstatic.com/mapfiles/place_api/icons/generic_business-71.png";
        id = 481f927c8ea30c24ae902a14dd85efd7e2bae1d1;
        name = "Kwik Fit";
        "opening_hours" =         {
            "open_now" = 1;
            "weekday_text" =             (
            );
        };
        photos =         (
                        {
                height = 608;
                "html_attributions" =                 (
                    "<a href=\"https://maps.google.com/maps/contrib/118136503820442451002\">Kwik Fit</a>"
                );
                "photo_reference" = "CmRdAAAAY152xIVsahSMoZgsMMN1IdIlMq6fbPeMCJ_1feXg1BIOhRTaW-s_wauDF8WSVPXnOG4dOR3nE9fLzqHmTmdoyKIAef_tZVFKOK43880DeItFOKNejmt_QaEamB4nX8uvEhCPQYbVi8day5vi1KSzGPFtGhT8KzkGs_FuA5ZM11lydRplhPM8uA";
                width = 1080;
            }
        );
        "place_id" = "ChIJ1zdwq2s_iEgR1fI1QvrsCas";
        reference = "CmRcAAAAkkARPnw1ApSjDPECBxsmTmcDDr5LESbSAWF0aNPvI2rX8BDJGfUj3dytKOotK2IbsCUaFbbhYZ8mgoDXfvYqtGliy2v06F2CarEAPSfD_25BGRYqUBsNKYiO05c-seGUEhDsuTEEt6PPKoZhmkBkj2VFGhQ-5vq-S7o73KmF2zw-MIJsPpWYgg";
        scope = GOOGLE;
        types =         (
            store,
            parking,
            "car_repair",
            "point_of_interest",
            establishment
        );
        vicinity = "1 Telford Road, East Kilbride";
    },
        {
        geometry =         {
            location =             {
                lat = "55.618894";
                lng = "-2.810683";
            };
        };
        icon = "https://maps.gstatic.com/mapfiles/place_api/icons/generic_business-71.png";
        id = 8ec3c7e9dc0da1d102d516107178cd440579ecff;
        name = "Kwik-Fit";
        "opening_hours" =         {
            "open_now" = 1;
            "weekday_text" =             (
            );
        };
        photos =         (
                        {
                height = 608;
                "html_attributions" =                 (
                    "<a href=\"https://maps.google.com/maps/contrib/102672183870059691928\">Kwik-Fit</a>"
                );
                "photo_reference" = "CmRdAAAAfbp51L51v3Mz4STPTBbUPvSy8b0GW_PYHQMcP6kXBDKIqhANAnVJINu3mdJk4mrEnG8-RSmR9SBa59z9qjRSxIVSEJapVWMSgGZzLHC3EVnib3-P3n1PnJyewKHVzR2tEhC5qWkLkJlXZl-6ETTap3GZGhSZCS6Wm9jEVAHx0nHwMTi6TNkVsw";
                width = 1080;
            }
        );
        "place_id" = ChIJqf1X7LyEh0gRK7GrZbR1qlI;
        reference = "CmRbAAAAoIW6Uer6wFdg9f9c_kRg0s5Wc-6wyUwg49CWQtn9hphJTfCqmidaP_unuejhxZBS_hChwfTHYWsspU7nOOFZx08cmzQ9bAW7cTp1N7vxepNfqR1YNybBBtB4romQAZO7EhCfxI62ia7XGtVPIyEPRSIPGhR4HnxB4lrDp1o4daDSipUAvFoG4Q";
        scope = GOOGLE;
        types =         (
            store,
            parking,
            "car_repair",
            "point_of_interest",
            establishment
        );
        vicinity = "Bridge Street, Galashiels";
    },
        {
        geometry =         {
            location =             {
                lat = "55.827528";
                lng = "-4.041783";
            };
        };
        icon = "https://maps.gstatic.com/mapfiles/place_api/icons/generic_business-71.png";
        id = 993dd6caf6e87b27c95b597170f82fc535db8464;
        name = "Scania Truck Rental";
        photos =         (
                        {
                height = 416;
                "html_attributions" =                 (
                    "<a href=\"https://maps.google.com/maps/contrib/111565851399356378888\">Ian McCully</a>"
                );
                "photo_reference" = "CmRdAAAAgxB25gl4CRnm6PENE9QPRq0WqPqIFUQCrvz7eOWsirTLMLZM_3gd_plKy9teW9AQdDIIZ3Ikmz96ADPiPD-wtDRvjDFMZl274q1HuA4zg8gVNi6QggypXkSPDdOdrfxUEhCf_qaIvJK0_iWgvnmT-TjcGhSRvsf9XiE5hkqcgwQdbKTm7oI5FA";
                width = 640;
            }
        );
        "place_id" = "ChIJ0YTxdlVqiEgRlNZz-R6gs9M";
        reference = "CnRnAAAAGNBVd-2Rzx_pF8lzxZ5WsI1qC8752BhlsKAXwS36PkmNVCZ4VQkH2FjmRDJ3swxoGLfJ0YmG4Cr1MACDFNaPSv0QdBo5zjIXQyRfytk77g2g0XVspPR7IhO9mQpuQHNCA-DDp5m1ph_ry1W3kt8IahIQiW-loOYmR9yACbxLie-eyhoUQF04W9ZNAeasiM5OqTqPlyDn6g8";
        scope = GOOGLE;
        types =         (
            parking,
            "car_repair",
            "point_of_interest",
            establishment
        );
        vicinity = "Melford Road, Bellshill";
    },
        {
        geometry =         {
            location =             {
                lat = "55.778158";
                lng = "-4.053103";
            };
        };
        icon = "https://maps.gstatic.com/mapfiles/place_api/icons/generic_business-71.png";
        id = 5b4e2e7beef36bc21e795144d512adb9cbc9ba54;
        name = "National Tyres and Autocare";
        "opening_hours" =         {
            "open_now" = 1;
            "weekday_text" =             (
            );
        };
        photos =         (
                        {
                height = 631;
                "html_attributions" =                 (
                    "<a href=\"https://maps.google.com/maps/contrib/100159584019554234022\">National Tyres and Autocare</a>"
                );
                "photo_reference" = "CmRdAAAALn7YnxOv_yKF3Sfkau09mJ1T7aY_L7La0E_2dxN9AGndS6evIYUPWCvYrQgSxD6Y69IsdGhkh08iY4gX0-YgXrbdtD0OBW6y8AjwVjYA34FLAAH9c122Kr_ImAGAmogREhDUOxeBxKmpZPcawyxxfnC9GhTJNNzPhS1xvgh_XPBXGOdhFhFgpQ";
                width = 789;
            }
        );
        "place_id" = ChIJrVjMcTMViEgRqc4gOlJfoDs;
        reference = "CnRuAAAAoOOZVebI5pz8rifXu3_n9RbZv0sobjodbPcP1DhknZcwTuZ_zCjch7l3D0tPqSO21S4wQlhYuH6tOrgBzHwkYBcRMS2-XP5r234IevwkdYV04gAk4BPBfuJMQIyrvASsDtRN9LJkPp8By7OleSyyqhIQco-kf732PwomY9loLvEtbBoUc2ZZKVbvMIYk0pVeFQronor3UM8";
        scope = GOOGLE;
        types =         (
            store,
            parking,
            "car_repair",
            "point_of_interest",
            establishment
        );
        vicinity = "Peacock Cross, Almada Street, Hamilton";
    }

2015-10-30 12:16:05.573 GooglePlaces[17141:989254]  name Yosemite National Park

The header file Where currentCenter is defined

    #import <UIKit/UIKit.h>
    #import <MapKit/MapKit.h>
    #import <CoreLocation/CoreLocation.h>
    #define kGOOGLE_API_KEY @"the key here"

    @interface AboutPlaceViewController : UIViewController <MKMapViewDelegate , CLLocationManagerDelegate>
    {
        CLLocationManager *locationManager;
        CLLocation *location;
// Where Current Centre is defined
        CLLocationCoordinate2D currentCentre;
        int currenDist;
        BOOL firstLaunch;

    }

    @property (weak, nonatomic) IBOutlet UILabel *placeLabell;

    @end

The Implementation file

#import "AboutPlaceViewController.h"
#import "ViewController.h"

@interface AboutPlaceViewController ()

@end

@implementation AboutPlaceViewController

- (void)viewDidLoad {
    [super viewDidLoad];

    locationManager = [[CLLocationManager alloc]init];
    locationManager.delegate = self;
    [locationManager setDistanceFilter:kCLDistanceFilterNone];
    [locationManager setDesiredAccuracy:kCLLocationAccuracyBest];
    [locationManager startUpdatingLocation];
     location = [locationManager location];
    //Do any additional setup after loading the view.
    NSDictionary *jsonDic = [[NSDictionary alloc]init];
    [self getApiResponse:&jsonDic];
    NSLog(@"jsonDic %@",jsonDic);
    NSDictionary *resultDic = [jsonDic[@"results"] objectAtIndex:0];
    NSString *name = resultDic[@"name"];
    NSLog(@" name %@", name);
    self.placeLabell.text = name;
 }
-(void)getApiResponse:(NSDictionary**)dataDictionary
 {
    // Where i dig into the Json array one example provided above
    NSDictionary *responseDict  = [[NSDictionary alloc]init];
    responseDict = [responseDict valueForKey:@"geometry"];
     NSArray *responseArray = [responseDict valueForKey:@"location"];
    NSDictionary *dict;
    // The for loop it doesnt go inside the for loop when debugging
    for(int i = 0; i< [responseDict count]; i++){
        dict = [responseArray objectAtIndex:i];
        NSLog(@"- %@",[responseArray objectAtIndex:i]);
     }
    // Where I declare but it returns nil :(
    currentCentre.latitude = [dict[@"lat"]doubleValue];
    currentCentre.longitude = [dict[@"lng"]doubleValue];

    NSString *api_key = kGOOGLE_API_KEY;
    NSString *urlString = [NSString stringWithFormat:@"https://maps.googleapis.com/maps/api/place/search/json?location=%f,%f&radius=50&types=%@&sensor=true&key=%@",currentCentre.latitude   , currentCentre.longitude,[NSString stringWithFormat:@"%i", currenDist],api_key];
    NSURL *url = [NSURL URLWithString:urlString];
    NSURLRequest *request = [NSURLRequest requestWithURL:url];
    NSURLResponse *response;
    NSError *error = nil;
    NSData *data = [NSURLConnection sendSynchronousRequest:
                    request returningResponse:&response error:&error];

    NSDictionary *jsonObject = [NSJSONSerialization JSONObjectWithData:data options:0 error:nil];

    dataDictionary = [[NSDictionary alloc]initWithDictionary:jsonObject copyItems:YES];
}


- (void)didReceiveMemoryWarning {
    [super didReceiveMemoryWarning];
    // Dispose of any resources that can be recreated.
}

The responseDict and the responseArray are also returning nil.

The currentCenter is returning nil and when I debug the code it doesn't go into the for loop. I have looked into the json format to find.

Answer 1

First on all: You have the following line:

 location = [locationManager location];

 You call the location straight after you initialise the manager.
 If you look at the location method description it says:

/*
 *  location
 *  
 *  Discussion:
 *      The last location received. Will be nil until a location has been received.
 */
 @property(readonly, nonatomic, copy, nullable) CLLocation *location;

IE you should wait till the first location has been received. Your class needs to implement CLLocationManagerDelegate and override:

- (void)locationManager:(CLLocationManager *)manager didUpdateLocations:(NSArray<CLLocation *> *)locations

Make sure that you requestAlwaysAuthorization before you access the user location

Moreover, What are you trying to do in this line?

 NSDictionary *responseDict = [responseDict  valueForKey:@"geometry"];

You are basically defining the dictionary and use it straight away.

Answer 2

Anamica first of all you need to get the latitude and longitude value correctly.If you don not get that,you can't get other details by passing latitude and longitude values.

Getting Latitude and longitude values from your response

NSString *lataddr=[[[responseDict objectForKey:@"geometry"]objectForKey:@"location"]objectForKey:@"lat"];
NSString *longaddr=[[[responseDict objectForKey:@"geometry"]objectForKey:@"location"]objectForKey:@"lng"];

Then pass these strings to your url.Now you can get the response without nil.

Also please remove below coding from your part

NSArray *responseArray = [responseDict valueForKey:@"location"];
NSDictionary *dict;
// The for loop it doesnt go inside the for loop when debugging
for(int i = 0; i< [responseDict count]; i++){
    dict = [responseArray objectAtIndex:i];
    NSLog(@"- %@",[responseArray objectAtIndex:i]);
 }
// Where I declare but it returns nil :(
currentCentre.latitude = [dict[@"lat"]doubleValue];
currentCentre.longitude = [dict[@"lng"]doubleValue];

instead of these part, you need to add

NSString *lataddr=[[[responseDict objectForKey:@"geometry"]objectForKey:@"location"]objectForKey:@"lat"];
NSString *longaddr=[[[responseDict objectForKey:@"geometry"]objectForKey:@"location"]objectForKey:@"lng"];

currentCentre.latitude = [lataddr doubleValue];
currentCentre.longitude = [longaddr doubleValue];

Above code for getting only single latitude and longitude value.

Now if you want to get the multiple latitude and longitude values for showing in map

NSMutableArray *arrayLat = [[NSMutableArray alloc]init];
NSMutableArray *arrayLng = [[NSMutableArray alloc]init];
NSDictionary *dict = [NSJSONSerialization JSONObjectWithData:responseData options:NSJSONReadingMutableContainers error:nil]; //This is for actually you are getting response to dict.
NSArray *arrayResponse = [dict copy];
NSLog(@"The response is - %@",arrayResponse);
for(int i=0;i<[arrayResponse count];i++)
{
   NSString *lataddr=[[[[[arrayResponse objectAtIndex:i]valueForKey:@"geometry"]valueForKey:@"location"]valueForKey:@"lat"];
   NSString *longaddr=[[[[[arrayResponse objectAtIndex:i]valueForKey:@"geometry"]valueForKey:@"location"]valueForKey:@"lng"];

   [arrayLat addObject:lataddr];
   [arrayLng addObject:longaddr];
}
for(int j=0;j<[arrayLat count];j++)
{
  currentCentre.latitude = [[arrayLat objectAtIndex:j] doubleValue];
  currentCentre.longitude = [[arrayLng objectAtIndex:j] doubleValue];
  NSString *api_key = kGOOGLE_API_KEY;
  NSString *urlString = [NSString stringWithFormat:@"https://maps.googleapis.com/maps/api/place/search/json?location=%f,%f&radius=50&types=%@&sensor=true&key=%@",currentCentre.latitude   , currentCentre.longitude,[NSString stringWithFormat:@"%i", currenDist],api_key];
  NSURL *url = [NSURL URLWithString:urlString];
  NSURLRequest *request = [NSURLRequest requestWithURL:url];
  NSURLResponse *response;
  NSError *error = nil;
  NSData *data = [NSURLConnection sendSynchronousRequest:
                request returningResponse:&response error:&error];

  NSDictionary *jsonObject = [NSJSONSerialization JSONObjectWithData:data options:0 error:nil];

  dataDictionary = [[NSDictionary alloc]initWithDictionary:jsonObject copyItems:YES];

}

All the best Anamica:-)

Answer 3

NSDictionary *responseDict  = [[NSDictionary alloc]init];
responseDict = [responseDict valueForKey:@"geometry"];

These two lines of code are utter nonsense. Throw away any thought of what you think what these do lines should do , but look at them and figure out what they are doing. How code responseDict possibly be anything other than nil after executing these two lines?

Answer 4

As I found(If I am right) you are trying to fetch values from son data form server.

You can use NSJsonSerilazation for getting data from NSData. Below is only a demo code for getting values

  NSData *yourDataFromServer;
    NSError*error;
    id records=  [NSJSONSerialization JSONObjectWithStream:yourDataFromServer options:NSJSONReadingMutableContainers error:&error];
    if (error!=nil)
    {
        if ([records isKindOfClass:[NSArray class]])  //Since you are getting Array Of Dictionary
        {
            NSDictionary *dictAtZeroIndex = records[0];
            NSDictionary *latLonDict= [dictAtZeroIndex valueForKey:@"geometry"];  //Again it will be a dictionary. For safety, Here you can again check wheter you are getting dictionary or array using "isKindOfClass"

        }
    }
    else{
        NSLog(@"error is :%@",error.localizedDescription);
    }

"yourDataFromServer" is NSData object coming from server. Might be helpful. Let me know if you are having any query. Use valueForKey with "latLonDict" for getting lat-lon values.