NSRange blockStartRange - ios

Question

Need your insight here...
This keeps crashing. Im calling a table on certain site, some say its the site that is causing but I can also make an exception. Can I get your two cents here?
NSRange blockStartRange = [pageContent rangeOfString:#"\t<table border=\"0\" cellpadding=\"4\" cellspacing=\"0\" id=\"table"];
NSRange blockEndRange = [pageContent rangeOfString:#"\t</table>" options:NSBackwardsSearch range:NSMakeRange(blockStartRange.location, [pageContent length] - blockStartRange.location)];
[HTMLString appendString:[pageContent substringWithRange:NSMakeRange(blockStartRange.location, blockEndRange.location + blockEndRange.length - blockStartRange.location)]];
// [HTMLString replaceOccurrencesOfString:#"width: 700px;" withString:#"" options:NSCaseInsensitiveSearch range:NSMakeRange(0, [HTMLString length])];
}
[webView loadHTMLString:HTMLString baseURL:[NSURL URLWithString:#"http://bowlatrabs.com/"]];
}
Error Log
2014-08-01 15:52:22.092 Bowl at Rabs[61401:90b] *** Terminating app due to uncaught exception 'NSRangeException', reason: '*** -[__NSCFString rangeOfString:options:range:locale:]: Range {2147483647, 2147542871} out of bounds; string length 59222'
*** First throw call stack:
(
0 CoreFoundation 0x0270b1e4 __exceptionPreprocess + 180
1 libobjc.A.dylib 0x020178e5 objc_exception_throw + 44
2 CoreFoundation 0x0270afbb +[NSException raise:format:] + 139
3 Foundation 0x000c38cd -[NSString rangeOfString:options:range:locale:] + 185
4 Foundation 0x000cf156 -[NSString rangeOfString:options:range:] + 69
5 Bowl at Rabs 0x0002d9e8 -[LeagueController viewDidLoad] + 920
6 UIKit 0x005dc33d -[UIViewController loadViewIfRequired] + 696
7 UIKit 0x005dc5d9 -[UIViewController view] + 35
8 UIKit 0x005f6942 -[UINavigationController _startCustomTransition:] + 778
9 UIKit 0x006038f7 -[UINavigationController _startDeferredTransitionIfNeeded:] + 688
10 UIKit 0x006044e9 -[UINavigationController __viewWillLayoutSubviews] + 57
11 UIKit 0x007450d1 -[UILayoutContainerView layoutSubviews] + 213
12 UIKit 0x0052c964 -[UIView(CALayerDelegate) layoutSublayersOfLayer:] + 355
13 libobjc.A.dylib 0x0202982b -[NSObject performSelector:withObject:] + 70
14 QuartzCore 0x04d9b45a -[CALayer layoutSublayers] + 148
15 QuartzCore 0x04d8f244 _ZN2CA5Layer16layout_if_neededEPNS_11TransactionE + 380
16 QuartzCore 0x04d8f0b0 _ZN2CA5Layer28layout_and_display_if_neededEPNS_11TransactionE + 26
17 QuartzCore 0x04cf57fa _ZN2CA7Context18commit_transactionEPNS_11TransactionE + 294
18 QuartzCore 0x04cf6b85 _ZN2CA11Transaction6commitEv + 393
19 QuartzCore 0x04cf7258 _ZN2CA11Transaction17observer_callbackEP19__CFRunLoopObservermPv + 92
20 CoreFoundation 0x026d336e __CFRUNLOOP_IS_CALLING_OUT_TO_AN_OBSERVER_CALLBACK_FUNCTION__ + 30
21 CoreFoundation 0x026d32bf __CFRunLoopDoObservers + 399
22 CoreFoundation 0x026b1254 __CFRunLoopRun + 1076
23 CoreFoundation 0x026b09d3 CFRunLoopRunSpecific + 467
24 CoreFoundation 0x026b07eb CFRunLoopRunInMode + 123
25 GraphicsServices 0x035765ee GSEventRunModal + 192
26 GraphicsServices 0x0357642b GSEventRun + 104
27 UIKit 0x004bdf9b UIApplicationMain + 1225
28 Bowl at Rabs 0x0000239c main + 76
29 libdyld.dylib 0x0325d725 start + 0
)
libc++abi.dylib: terminating with uncaught exception of type NSException
(lldb)

Answer 1

You need to handle the case where the strings do not exist. Apple's documentation for the rangeOfString: method says: "Returns {NSNotFound, 0} if aString is not found or is empty (#"")."
So you need to check to see if the returned ranges have range.location == NSNotFound and handle that in whatever way is best.

Answer 2

Other way to check is using NSRangeFromString
NSRangeFromString: Returns a range from a textual representation.
If the string passed into NSRangeFromString does not represent a valid range, it will return a range with its location and length set to 0.
NSString *string = #"invalid";
NSRange range = NSRangeFromString(string);
// {.location=0, .length=0}
You might check nshipster/range