objective c - How to fix long NSString crash? -

in app i'm working on i'm reading numerical values text file in loop doing calculations , appending result results string.

the file has 22050 values in it. noticed above number of loops/values appended (~5300) tends crash.

i thought perhaps have memory leak, got rid of string appending , worked fine. tried getting rid of string appending , app crashed. have break point on exceptions , don't exception.

i wanted make sure started new project. put there 1 uibutton when pushed calls piece of code:

- (ibaction)testpressed:(id)sender {     nsstring *teststring = @"";      (int = 0; < 22050; i++)     {         teststring = [teststring stringbyappendingstring:@"12.34567890\n"];     }      nslog(@"%@", teststring); } 

i have break point on nslog line. app crashes before.

is there limit on nsstring length? use memory?

the problem creating new string in every iteration. there 2 options fix this: either use mutable string create result:

nsmutablestring *teststring = [nsmutablestring string];  (int = 0; < 22050; i++) {     [teststring appendstring:@"12.34567890\n"]; }  nslog(@"%@", teststring); 

... or use autorelease pool remove instances in loop:

nsstring *teststring = @"";  (int = 0; < 22050; i++) {     @autoreleasepool {         teststring = [teststring stringbyappendingstring:@"12.34567890\n"];     } }  nslog(@"%@", teststring); 

please note included second version demonstrate why problem occurred in first place , how fix it. still inefficient creates 22049 temporary strings average length of 120,000 characters.