ios 不區分字符串大小寫的比較

        NSString *str;
        // 使用stringWithFormat生成一格式化字符串
        str = [NSString stringWithFormat:@"This is %@","John"];
        NSLog(@"str--->%@",str);
        // 字符串長度length;
        NSLog(@"The length of this string is %@",[str length]);
        // 字符串比較 isEqualToString, 返回NO(false)，isEqualToString區分大小寫
        BOOL isequal = [str isEqualToString:@"this is John"];
         
        // 字符串序列比列 compare,返回結果NSComparisonResult
        // type enum _NSComparisonResult{
        // NSOrderedAscending = -1,
        // NSOrderedSame,
        // NSOrderedDescending
        // }
        int result = [@"bool" compare:@"cool"];
        NSLog(@"The result is %d",result);
         
        // compare 比較規則options
        // NSLiteralSearch 區分大小寫(完全比較)
        // NSCaseInsensitiveSearch 不區分大小寫
        // NSNumericSearch 只比較字符串的個數，而不比較字符串的字面值
        int result1 = [@"This is John" compare:@"this is John" options:NSCaseInsensitiveSearch | NSNumericSearch];
        NSLog(@"The result is %d",result1);
         
        // 字符串開頭是否包括另一字符串 hasPrefix,返回結果YES(true)
        BOOL isHas = [str hasPrefix:@"This"];
        // 字符串結尾是否包括另一字符串 hasSuffix,返回結果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);