字符串处理2022-02-17

1 字符串去除表情符号

将字符串进行utf8解码, 然后将每个字符的utf8编码的第一个char转为int, 查看是不是4294967280(0xF0FFFFFF), 如果是表情符号, 则跳过3个utf8的char(因为一个表情符号utf8解码后是4个char), 读下一个字符.
表情符号的utf8编码在 http://punchdrunker.github.io/iOSEmoji/table_html/vehicle.html
这里只是判断开头是0xF0的表情符号, 其它表情符号没有处理

+ (NSString *)filterEmoji:(NSString *)string
{
    NSUInteger len = [string lengthOfBytesUsingEncoding:NSUTF8StringEncoding];
    const char *utf8 = [string UTF8String];
    char *newUTF8 =malloc(sizeof(char)*len);
    int j = 0;
    for (int i =0; i < len; i++) {
        unsigned int c = utf8[i];
        BOOL isControlChar =NO;
        if (c==4294967280) {
            i = i+3;
            isControlChar = YES;
        }
        if (!isControlChar) {
            newUTF8[j] = utf8[i];
            j++;
        }
    }
    newUTF8[j] = '\0';
    NSString *encrypted = [[NSString alloc]initWithCString:(const char*)newUTF8 encoding:NSUTF8StringEncoding];
    return encrypted;
}