How can I get a string between 2 known strings? For example:
<id> 100 </id>
I want to get the 100 from this string.
I have try this code but it doesn´t work. The NSLog is:
<id>100
Code:
NSString *serverOutput = @"<id>100</id>";
NSRange start = [serverOutput rangeOfString:@"<id>"];
NSRange end = [serverOutput rangeOfString:@"</id>"];
NSLog(@"%@",[serverOutput substringWithRange:NSMakeRange(start.location, end.location)]);
You where nearly there, but the range location is the start of the not the end. So you have to add the length of the range.
Since the you moved the start of you string, you need to short the length with the offset:
NSString *serverOutput = @"<id>100</id>";
NSRange startRange = [serverOutput rangeOfString:@"<id>"];
NSRange endRange = [serverOutput rangeOfString:@"</id>"];
NSInteger start = NSMaxRange (startRange);
NSInteger length = endRange.location - startRange.length;
NSLog(@"%@", [serverOutput substringWithRange:NSMakeRange(start, length)]);
end as length might add clarity for future readers.
NSMaxRange(startRange) would be preferred over startRange.location + startRange.length. No reason to do the math yourself when a function already exists to do it for you.In Swift:
extension String {
func slice(from: String, to: String) -> String? {
return (range(of: from)?.upperBound).flatMap { substringFrom in
(range(of: to, range: substringFrom..<endIndex)?.lowerBound).map { substringTo in
String(self[substringFrom..<substringTo])
}
}
}
}
Input
let serverOutput = "<id>100</id>"
let resultString = serverOutput.slice(from: "<id>", to: "</id>")
print(resultString)
Output
100
This is how NSRange defined:
typedef struct _NSRange {
NSUInteger location;
NSUInteger length;
} NSRange;
So, if you want to get 100, you should substring like this:
NSRange substringRange = NSMakeRange(start.location + start.length, end.location - start.length);
NSLog(@"%@", [serverOutput substringWithRange:substringRange]);
NSString *serverOutput = @"<id>100</id>";
serverOutput = [serverOutput stringByReplacingOccurrencesOfString:@"<id>" withString:@""];
serverOutput = [serverOutput stringByReplacingOccurrencesOfString:@"</id>" withString:@""];
NSLog(@"%@",serverOutput);
I think that you should use a regular expression.
NSString *serverOutput = @"<id>100</id>";
NSString *pattern = @"<id>([0-9]+)</id>";
NSError *error;
NSRegularExpression *regex = [NSRegularExpression regularExpressionWithPattern:pattern
options:NSRegularExpressionCaseInsensitive
error:&error];
NSTextCheckingResult *match = [regex firstMatchInString:serverOutput
options:NSMatchingReportProgress
range:NSMakeRange(0, serverOutput.length)];
if (!error && match && match.numberOfRanges >= 2) {
NSRange range = [match rangeAtIndex:1];
NSLog(@"%@", [serverOutput substringWithRange:range]);
}
You want to start at the end of the first string, so you just need to change:
NSLog(@"%@",[serverOutput substringWithRange:NSMakeRange(start.location, end.location)]);
To:
NSLog(@"%@",[serverOutput substringWithRange:NSMakeRange(NSMaxRange(start), end.location - start.length)]);
Notice that I also subtracted the length of the start string because we just offset by that much.
