Regex in objective C - ios

Question

I want to extract only the names from the following string
bob!33#localhost #clement!17#localhost jack!03#localhost
and create an array [#"bob", #"clement", #"jack"].
I have tried NSString's componentsseparatedbystring: but it didn't work as expected. So I am planning to go for regEx.
How can I extract strings between ranges and add it to an array
using regEx in objective C?
The initial string might contain more than 500 names, would it be a
performance issue if I manipulate the string using regEx?

Answer 1

You can do it without regex as below (Assuming ! sign have uniform pattern in your all words),
NSString *names = #"bob!33#localhost #clement!17#localhost jack!03#localhost";
NSArray *namesarray = [names componentsSeparatedByString:#" "];
NSMutableArray *desiredArray = [[NSMutableArray alloc] initWithCapacity:0];
[namesarray enumerateObjectsUsingBlock:^(id obj, NSUInteger idx, BOOL *stop) {
NSRange rangeofsign = [(NSString*)obj rangeOfString:#"!"];
NSString *extractedName = [(NSString*)obj substringToIndex:rangeofsign.location];
[desiredArray addObject:extractedName];
}];
NSLog(#"%#",desiredArray);
output of above NSLog would be
(
bob,
"#clement",
jack
)
If you still want to get rid of # symbol in above string you can always replace special characters in any string, for that check this
If you need further help, you can always leave comment

Answer 2

NSMutableArray* nameArray = [[NSMutableArray alloc] init];
NSArray* youarArray = [yourString componentsSeparatedByString:#" "];
for(NSString * nString in youarArray) {
NSArray* splitObj = [nString componentsSeparatedByString:#"!"];
[nameArray addObject:[splitObj[0]]];
}
NSLog(#"%#", nameArray);

Answer 3

I saw the other solutions and it seemed no one tried to use real regular expressions here, so I created a solution which uses it, maybe you or someone else can use it as a possible idea in the future:
NSString *_names = #"bob!33#localhost #clement!17#localhost jack!03#localhost";
NSError *_error;
NSRegularExpression *_regExp = [NSRegularExpression regularExpressionWithPattern:#" ?#?(.*?)!\\d{2}#localhost" options:NSRegularExpressionCaseInsensitive error:&_error];
NSMutableArray *_namesOnly = [NSMutableArray array];
if (!_error) {
NSLock *_lock = [[NSLock alloc] init];
[_regExp enumerateMatchesInString:_names options:NSMatchingReportProgress range:NSMakeRange(0, _names.length) usingBlock:^(NSTextCheckingResult *result, NSMatchingFlags flags, BOOL *stop) {
if (result.numberOfRanges > 1) {
if ([_lock tryLock]) [_namesOnly addObject:[_names substringWithRange:[result rangeAtIndex:1]]], [_lock unlock];
}
}];
} else {
NSLog(#"error : %#", _error);
}
the result can be logged...
NSLog(#"_namesOnly : %#", _namesOnly);
...and that will be:
_namesOnly : (
bob,
clement,
jack
)

Answer 4

Or even something as simple as this will do the trick:
NSString *strNames = #"bob!33#localhost #clement!17#localhost jack!03#localhost";
strNames = [[strNames componentsSeparatedByCharactersInSet:[[NSCharacterSet letterCharacterSet] invertedSet]]
componentsJoinedByString:#""];
NSArray *arrNames = [strNames componentsSeparatedByString:#"localhost"];
NSLog(#"%#", arrNames);
Output:
(
bob,
clement,
jack,
""
)
NOTE: Ignore the last element index while iterating or whatever
Assumption:
"localhost" always comes between names
I know it ain't so optimized but it's one way to do this