ios 字符串的比较

  // 声明一个NSString  NSString *str;  // 使用stringWithFormat生成一格式化字符串  str = [NSString stringWithFormat:@"This is %@","John"];  NSLog(@"str--->%@",str);  // 字符串长度length;  NSLog(@"The length of this string is %@",[str length]);  // 字符串比较 isEqualToString, 返回NO(false)，isEqualToString区分大小写  BOOL isequal = [str isEqualToString:@"this is John"];    // 字符串序列比列 compare,返回结果NSComparisonResult  // type enum _NSComparisonResult{  //     NSOrderedAscending = -1,  //     NSOrderedSame,  //     NSOrderedDescending          // }  int result = [@"bool" compare:@"cool"];  NSLog(@"The result is %d",result);    // compare 比较规则options  // NSLiteralSearch 区分大小写(完全比较)  // NSCaseInsensitiveSearch 不区分大小写  // NSNumericSearch 只比较字符串的个数，而不比较字符串的字面值  int result1 = [@"This is John" compare:@"this is John" options:NSCaseInsensitiveSearch | NSNumericSearch];  NSLog(@"The result is %d",result1);    // 字符串开头是否包括另一字符串 hasPrefix,返回结果YES(true)  BOOL isHas = [str hasPrefix:@"This"];  // 字符串结尾是否包括另一字符串 hasSuffix,返回结果YES(true)  BOOL isHas = [str hasSuffix:@"John"];    // 查找字符串在另一字符串中的位置  NSRange range = [str rangeOfString:@"is" options:NSCaseInsensitiveSearch];  NSLog(@"The location in the string named 'str' of 'is' is @d",range.location);