iOS unicode编码解码

//Unicode转化为汉字:

+(NSString *)replaceUnicode:(NSString*)unicodeStr{
    NSString *tempStr1=[unicodeStr stringByReplacingOccurrencesOfString:@"\\u"withString:@"\\U"];
    NSString *tempStr2=[tempStr1 stringByReplacingOccurrencesOfString:@"\""withString:@"\\\""];
NSString *tempStr3=[[@"\"" stringByAppendingString:tempStr2]stringByAppendingString:@"\""];
NSData *tempData=[tempStr3 dataUsingEncoding:NSUTF8StringEncoding];
NSString* returnStr =[NSPropertyListSerialization propertyListFromData:tempData
                                                     mutabilityOption:NSPropertyListImmutable
                                                               format:NULL
                                                     errorDescription:NULL];

return [returnStr stringByReplacingOccurrencesOfString:@"\\r\\n"withString:@"\n"];

}

//中文转unicode

- (NSString *) utf8ToUnicode:(NSString *)string{

NSUInteger length = [string length];
NSMutableString *str = [NSMutableString stringWithCapacity:0];
for (int i = 0;i < length; i++){
    NSMutableString *s = [NSMutableString stringWithCapacity:0];
    unichar _char = [string characterAtIndex:i];
    // 判断是否为英文和数字
    if (_char <= '9' && _char >='0'){
        [s appendFormat:@"%@",[string substringWithRange:NSMakeRange(i,1)]];
    }else if(_char >='a' && _char <= 'z'){
        [s appendFormat:@"%@",[string substringWithRange:NSMakeRange(i,1)]];
    }else if(_char >='A' && _char <= 'Z')
    {
        [s appendFormat:@"%@",[string substringWithRange:NSMakeRange(i,1)]];
    }else{
        // 中文和字符
        [s appendFormat:@"\\u%x",[string characterAtIndex:i]];
        // 不足位数补0 否则解码不成功
        if(s.length == 4) {
            [s insertString:@"00" atIndex:2];
        } else if (s.length == 5) {
            [s insertString:@"0" atIndex:2];
        }
    }
    [str appendFormat:@"%@", s];
}
return str;

}