最近项目中碰到的问题，在发送网络请求时，由于用户输入了emoji表情，服务端返回错误提示信息。为了解决服务器不能验证emoji编码的问题，需要在本地进行emoji的输入控制（正常情况下应该由服务器在数据库中添加emoji对应的转码表以支持客户端发送emoji表情），在网上搜了下iOS端解决办法如下：
1.当用户切换键盘为Emoji表情时，输入的表情不响应（即表情符号不显示到UITextView或UITextField）。这里可以通过UITextView或UITextField的回调和是否为emoji键盘：
[[[textView textInputMode] primaryLanguage] isEqualToString:@"emoji"]- (BOOL)textField:(UITextField *)textField shouldChangeCharactersInRange:(NSRange)range replacementString:(NSString *)string{ //不支持系统表情的输入 if ([[[UITextInputMode currentInputMode ]primaryLanguage] isEqualToString:@"emoji"]) { return NO; } return YES;}

2.通过过滤用户输入的emoji来实现
//过滤表情+ (NSString *)filterEmoji:(NSString *)string { NSUInteger len = [string lengthOfBytesUsingEncoding:NSUTF8StringEncoding]; const char *utf8 = [string UTF8String]; char *newUTF8 = malloc( sizeof(char) * len ); int j = 0; //0xF0(4) 0xE2(3) 0xE3(3) 0xC2(2) 0x30---0x39(4) for ( int i = 0; i < len; i++ ) { unsigned int c = utf8; BOOL isControlChar = NO; if ( c == 4294967280 || c == 4294967089 || c == 4294967090 || c == 4294967091 || c == 4294967092 || c == 4294967093 || c == 4294967094 || c == 4294967095 || c == 4294967096 || c == 4294967097 || c == 4294967088 ) { i = i + 3; isControlChar = YES; } if ( c == 4294967266 || c == 4294967267 ) { i = i + 2; isControlChar = YES; } if ( c == 4294967234 ) { i = i + 1; isControlChar = YES; } if ( !isControlChar ) { newUTF8[j] = utf8; j++; } } newUTF8[j] = '\0'; NSString encrypted = [NSString stringWithCString:(const char)newUTF8 encoding:NSUTF8StringEncoding]; free( newUTF8 ); return encrypted;}

3.通过判断用户输入的字符串时候含有表情来进行对应的操作
//是否含有表情+ (BOOL)stringContainsEmoji:(NSString *)string{ __block BOOL returnValue = NO; [string enumerateSubstringsInRange:NSMakeRange(0, [string length]) options:NSStringEnumerationByComposedCharacterSequences usingBlock:^(NSString *substring, NSRange substringRange, NSRange enclosingRange, BOOL *stop) { const unichar hs = [substring characterAtIndex:0]; if (0xd800 <= hs && hs <= 0xdbff) { if (substring.length > 1) { const unichar ls = [substring characterAtIndex:1]; const int uc = ((hs - 0xd800) * 0x400) + (ls - 0xdc00) + 0x10000; if (0x1d000 <= uc && uc <= 0x1f77f) { returnValue = YES; } } } else if (substring.length > 1) { const unichar ls = [substring characterAtIndex:1]; if (ls == 0x20e3) { returnValue = YES; } } else { if (0x2100 <= hs && hs <= 0x27ff) { returnValue = YES; } else if (0x2B05 <= hs && hs <= 0x2b07) { returnValue = YES; } else if (0x2934 <= hs && hs <= 0x2935) { returnValue = YES; } else if (0x3297 <= hs && hs <= 0x3299) { returnValue = YES; } else if (hs == 0xa9 || hs == 0xae || hs == 0x303d || hs == 0x3030 || hs == 0x2b55 || hs == 0x2b1c || hs == 0x2b1b || hs == 0x2b50) { returnValue = YES; } } }]; return returnValue;}

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文／黄二峰（简书作者）原文链接：http://www.jianshu.com/p/2597d4c3a183著作权归作者所有，转载请联系作者获得授权，并标注“简书作者”。