How to get substring of NSString?

Question

If I want to get a value from the NSString @"value:hello World:value", what should I use?

The return value I want is @"hello World".

Answer 1

Option 1:

NSString *haystack = @"value:hello World:value"; NSString *haystackPrefix = @"value:"; NSString *haystackSuffix = @":value"; NSRange needleRange = NSMakeRange(haystackPrefix.length,                                   haystack.length - haystackPrefix.length - haystackSuffix.length); NSString *needle = [haystack substringWithRange:needleRange]; NSLog(@"needle: %@", needle); // -> "hello World" 

Option 2:

NSRegularExpression *regex = [NSRegularExpression regularExpressionWithPattern:@"^value:(.+?):value$" options:0 error:nil]; NSTextCheckingResult *match = [regex firstMatchInString:haystack options:NSAnchoredSearch range:NSMakeRange(0, haystack.length)]; NSRange needleRange = [match rangeAtIndex: 1]; NSString *needle = [haystack substringWithRange:needleRange]; 

This one might be a bit over the top for your rather trivial case though.

Option 3:

NSString *needle = [haystack componentsSeparatedByString:@":"][1]; 

This one creates three temporary strings and an array while splitting.

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All snippets assume that what's searched for is actually contained in the string.

Answer 2

Here's a slightly less complicated answer:

NSString *myString = @"abcdefg"; NSString *mySmallerString = [myString substringToIndex:4]; 

See also substringWithRange and substringFromIndex