Can not read the specific values of json file in objective c

Question

I have downloaded the json files in my App Folder and I want to read that files from my App Folder to print specific values.

Files are located like this : /var/mobile/Containers/Data/Application/63E66EE9-9A1B-4D4D-AEF6-F8C54D159ED0/Library/NoCloud/MyApp/MyFolder/DTS.json

This is what file contains: [{"value":0}] However the file contents are read and printed in console as I have mentioned below but when I read specific value it gives null

NSURL *libraryDirURL = [[NSFileManager.defaultManager URLsForDirectory:NSLibraryDirectory inDomains:NSUserDomainMask] lastObject];
NSURL *urlDTSK = [libraryDirURL URLByAppendingPathComponent:@"NoCloud/MyApp/MyFolder/DTS.json"];
NSString *filePathDTS = [NSString stringWithContentsOfURL:urlDTSK encoding:NSUTF8StringEncoding error:nil];
NSLog(@"This is Dts PATH %@", filePathDTS);
NSData *dataDTS = [NSData dataWithContentsOfFile:filePathDTS];
NSLog(@"here is DTS data  %@", dataDTS); //this shows null
NSDictionary *jsonDTS = [NSJSONSerialization JSONObjectWithData:dataDTS options:kNilOptions error:nil];
NSLog(@"here is jason DTS %@", jsonDTS);
NSMutableArray *DTSvalue = [jsonDTS valueForKeyPath: @"Value"];
DTSValueIs = DTSvalue[0];
NSLog(@"here is DTS Value first%@", DTSvalue[0]);
NSLog(@"here is DTS value is%@", DTSValueIs);

This shows This is Dts contents [{"value":0}] 2018-06-11 17:04:40.940006+0500 Muslims 365[3356:819935] here is DTS data (null)

Answer 1

So libraryDirURL is a path to library. Then urlDTSK is a path to specific file in in the library. Then filePathDTS is CONTENTS of that file in library as UTF8 string...

But dataDTS is contents of file at location written in file at filePathDTS . I believe the code should be:

NSData *dataDTS = [NSData dataWithContentsOfFile: urlDTSK.path];

Answer 2

The error occurs because you are getting an NSString from a file URL and then you are getting NSData from that string as file path which cannot work. Omit that step:

NSURL *libraryDirURL = [[NSFileManager.defaultManager URLsForDirectory:NSLibraryDirectory inDomains:NSUserDomainMask] lastObject];
NSURL *urlDTSK = [libraryDirURL URLByAppendingPathComponent:@"NoCloud/MyApp/MyFolder/DTS.json"];
NSData *dataDTS = [NSData dataWithContentsOfURL: urlDTSK];

By the way the retrieved JSON is an array, you get the value for key Value from the first element which seems to be a numeric value ( NSNumber ).

And handle the error!

NSError *error;
NSArray *jsonArray = [NSJSONSerialization JSONObjectWithData:dataDTS options:kNilOptions error:&error];
if (error) { NSLog(@"%@", error); }
NSNumber *dtsValue = jsonArray[0][@"value"];
NSLog(@"here is DTS value: %@", dtsValue); // here is DTS value: 0

Answer 3

In your code, you must allocate

NSMutableArray *DTSvalue = [NSMutableArray alloc]init];

before use.