objective c - NSMutableDictionary objectForKey returns null with correct key -

im having weird problem nsdictionary, take @ code , console output , see yourself.

for (int y = 0; y < self.tileproperties.allkeys.count; ++y) {  //i go on keys in nsdictionary,self.tileproperties.         nsstring *string = [self.tileproperties.allkeys objectatindex:y];          nslog(@"keys %@",string);         nslog(@"objects in array %@",[self.tileproperties objectforkey:string]);     }      nslog(@"object in array 2 %@",[self.tileproperties objectforkey:@"496"]); 

this console outputs.

2016-09-12 17:23:00.822 greatgrimbeta[1043:130572] keys 496 2016-09-12 17:23:00.822 greatgrimbeta[1043:130572] objects in array { fire = 7; } 2016-09-12 17:23:00.823 greatgrimbeta[1043:130572] object in array 2 (null) 

why getting null same key used in loop?

thank help!

the answer of joshcaswell

nsnumber *num = [nsnumber numberwithint:496]; nslog(@"object in array 2 %@",[self.tileproperties objectforkey:num]);  2016-09-12 18:14:43.217 greatgrimbeta[1156:149732] {     fire = 7; }