ios 不区分字符串大小写的比较

        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);