Unrecognized selector sent to instance with TableViewController - ios

Question

I'm very new to Obj-c and I'm now creating a tableview to show what I have parsed from Json. Here's the code:
#import "ClasstableViewController.h"
#interface ClasstableViewController ()
#end
#implementation ClasstableViewController
- (void)viewDidLoad {
[super viewDidLoad];
self.title = #"JSONRead";
NSString *testUrl = #"example.com";
NSURL *url = [NSURL URLWithString:testUrl];
NSURLRequest *request = [[NSURLRequest alloc]initWithURL:url cachePolicy:NSURLRequestUseProtocolCachePolicy
timeoutInterval:10];
NSData *JSONData = [NSURLConnection sendSynchronousRequest:request returningResponse:nil error:nil];
NSArray *jsonResult = [NSJSONSerialization JSONObjectWithData:JSONData options:kNilOptions error:nil];
self.data = jsonResult;
NSMutableArray *_names = [NSMutableArray array];
for (id item in jsonResult)
[_names addObject:[NSString stringWithFormat:#"%#", item[#"Mon"]]];
self.names = _names;
}
- (NSInteger)numberOfSectionsInTableView:(UITableView *)tableView {
// Return the number of sections.
return 1;
}
- (NSInteger)tableView:(UITableView *)tableView numberOfRowsInSection:(NSInteger)section {
// Return the number of rows in the section.
return [self.names count];
}
- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath {
static NSString *CellIdentifier = #"Cell";
UITableViewCell *cell = [tableView dequeueReusableCellWithIdentifier:CellIdentifier];
if (!cell)
cell = [[UITableViewCell alloc] initWithStyle:UITableViewCellStyleDefault reuseIdentifier:CellIdentifier];
cell.textLabel.text = self.names[indexPath.row];
return cell;
}
and I have change my tableview to the correct class in the identity inspector to ClasstableViewController, I see others have resolve their issues with this solution.
but I'm still getting this:
-[__NSCFString objectForKeyedSubscript:]: unrecognized selector sent to instance 0x7fd8835691c0
*** Terminating app due to uncaught exception 'NSInvalidArgumentException', reason: '-[__NSCFString objectForKeyedSubscript:]: unrecognized selector sent to instance 0x7fd8835691c0'
anyone have any idea why?

Answer 1

Probably your NSArray *jsonResult is an array of NSStrings, or contain some NSStrings as objects. So when you do
for (id item in jsonResult)
[_names addObject:[NSString stringWithFormat:#"%#", item[#"Mon"]]];
you are supposing that item is a NSDictionary, but it isn't.

Answer 2

for (id item in jsonResult)
[_names addObject:[NSString stringWithFormat:#"%#", item[#"Mon"]]];
item is NSString not NSDictionary,use like below
for (id item in jsonResult)
[_names addObject:[NSString stringWithFormat:#"%#", item]];
Use JSONEditor to check the JSON.