--------------------------------------------------------------*/
第一种:
字符串: urlString
NSScanner *scanner = [NSScanner scannerWithString:urlString];
[scanner scanUpToCharactersFromSet:[NSCharacterSet decimalDigitCharacterSet] intoString:nil];
int number;
[scanner scanInt:&number];
NSString *num=[NSString stringWithFormat:@"%d",number];

/** --------

第二种:

字符串: urlString

NSCharacterSet* nonDigits =[[NSCharacterSet decimalDigitCharacterSet] invertedSet];
int remainSecond =[[urlString stringByTrimmingCharactersInSet:nonDigits] intValue];
NSLog(@" num %d ",remainSecond);