Extract a 8 digit number from string of variable size - objective-c

Question

I have a string of undetermined size which contains a 8 digit number. Example:
This is 123456 a string
This is a new string 123456
123456 This is another string
How can I extract the integer value of such number?

Answer 1

NSString has an instance method -integerValue which returns the integer value extracted from the string's contents. So [#"123456" integerValue] will return 123456.

Answer 2

I think what you want is an NSScanner. Have the scanner scan up to the first occurrence of the decimalDigitCharacterSet and then use scanInteger: to get the NSInteger value it finds.

Answer 3

You can use regular expressions to pull numbers of any given format out of a string. If you just wanted to grab one integer from any given string (in this case, the first integer):
NSString* str = #"This is 123456 a string";
NSRegularExpression* regex = [NSRegularExpression regularExpressionWithPattern:#".*?(\\d+).*?" options:NULL error:nil];
NSArray* results = [regex matchesInString:str options:NULL range:NSMakeRange(0, [str length])];
NSString* str2 = [str substringWithRange:[(NSTextCheckingResult*)[results objectAtIndex:0] rangeAtIndex:1]];
NSLog(#"%#",str2);
NSInteger intResult = [str2 integerValue];

Answer 4

Extract a number of the given digits from a string of undeterminate length.
#import <Foundation/Foundation.h>
NSNumber* numberFromStringWithDigits(NSString* string, NSUInteger digits)
{
NSScanner *scanner = [NSScanner scannerWithString:string];
NSCharacterSet *allowed = [NSCharacterSet decimalDigitCharacterSet];
while ([scanner isAtEnd] == NO) {
NSString *buffer;
if ([scanner scanCharactersFromSet:allowed intoString:&buffer]) {
if ([buffer length]==digits){
return [NSNumber numberWithInt:[buffer integerValue]];
}
} else {
[scanner setScanLocation:([scanner scanLocation] + 1)];
}
}
return nil;
}
int main(int argc, char *argv[]) {
#autoreleasepool {
NSString *url = #"http://garb23age.com/x555xx/xx12345678xxxxxx";
NSDate *startTime = [NSDate date];
NSNumber *n = numberFromStringWithDigits(url,8);
NSTimeInterval elapsedTime = [startTime timeIntervalSinceNow];
NSLog(#"%# in %f seconds",n,-elapsedTime); // 12345678 in 0.000188 seconds
}
}
#Bri An C: probably what you want is to extract the parameterString of the NSURL. Maybe you should post the URL to ask for alternate solutions.