Case insensitive comparison NSString

Question

Can anyone point me to any resources about case insensitive comparison in Objective C? It doesn\'t seem to have an equivalent method to str1.equalsIgnoreCase(str2)

Answer 1

Converting Jason Coco's answer to Swift for the profoundly lazy :)

if ("Some String" .caseInsensitiveCompare("some string") == .OrderedSame)
{
  // Strings are equal.
}

Answer 2

- (NSComparisonResult)caseInsensitiveCompare:(NSString *)aString

Answer 3

 NSString *stringA;
 NSString *stringB;

 if (stringA && [stringA caseInsensitiveCompare:stringB] == NSOrderedSame) {
     // match
 }

Note: stringA && is required because when stringA is nil:

 stringA = nil;
 [stringA caseInsensitiveCompare:stringB] // return 0

and so happens NSOrderedSame is also defined as 0.

The following example is a typical pitfall:

 NSString *rank = [[NSUserDefaults standardUserDefaults] stringForKey:@"Rank"];
 if ([rank caseInsensitiveCompare:@"MANAGER"] == NSOrderedSame) {
     // what happens if "Rank" is not found in standardUserDefaults
 }

Answer 4

On macOS you can simply use -[NSString isCaseInsensitiveLike:], which returns BOOL just like -isEqual:.

if ([@"Test" isCaseInsensitiveLike: @"test"])
    // Success

Answer 5

Alternate solution for swift:

To make both UpperCase:

e.g:

if ("ABcd".uppercased() == "abcD".uppercased()){
}

or to make both LowerCase:

e.g:

if ("ABcd".lowercased() == "abcD".lowercased()){
}

Answer 6

An alternative if you want more control than just case insensitivity is:

[someString compare:otherString options:NSCaseInsensitiveSearch];

Numeric search and diacritical insensitivity are two handy options.