实现方法如下
NSString *string=@"440822199111114472";
//截取年份
NSRange range = NSMakeRange(6, 4);
NSString *year = [string substringWithRange:range];
//截取月份
NSRange range1 = NSMakeRange(10, 2);
NSString *month = [string substringWithRange:range1];
//截取日
NSRange range2 = NSMakeRange(12, 2);
NSString *day = [string substringWithRange:range2];
NSLog(@"%@-%@-%@",year,month,day);