由于最近做人脸识别，后台上传到服务器的时候，发现补位码”=“出现的时候，人脸识别的注册图无法上传成功，经过测试发现，只要有补位码出现"="的时候就会无法上传成功，和图片的特征，人脸数据的矩阵方差没啥关系，
这个记录一下，过滤一些会被后台误认为是空字符的特殊字符 ”\r“ ”\n“ ”="

UIImage 转码到 NSData

-(void)reuploadAction:(UIButton *)sender{
    [XNHUD show];
   //压缩到指定的KB 列如下面的200 直接 pod 'YQImageCompressor' 可以引入
    [YQImageCompressTool CompressToDataAtBackgroundWithImage:self.cameraBtn.imageView.image
                                                     ShowSize:self.cameraBtn.imageView.image.size
                                                     FileSize:200
                                                        block:^(NSData *resultData) {
         if(resultData) {
             NSString *encodedImageStr = [resultData base64EncodedStringWithOptions:NSDataBase64Encoding64CharacterLineLength];
             [self updateFace:encodedImageStr]; //上传服务器，这个观众们可以忽略我就不写这个方法了
           }
     }];
}

-(NSString *)removeSpaceAndNewline:(NSString *)str
{
    NSString *temp = [str stringByReplacingOccurrencesOfString:@" " withString:@""];
    temp = [temp stringByReplacingOccurrencesOfString:@"\r" withString:@""];
    temp = [temp stringByReplacingOccurrencesOfString:@"\n" withString:@""];
    temp = [temp stringByReplacingOccurrencesOfString:@"=" withString:@"" options:NSBackwardsSearch range:NSMakeRange(str.length-3, 3)];
    return temp;
}

解析过滤之后的base64 检验是否是规范的base64 ，主要就是这个方法能够成功把一些不规范的base64转成图片

//我自己写的方法 ，这边的str 就是Base64的字符串，命名不太好，各位勿喷
- (UIImage *)stringToImage:(NSString *)str {
   NSData *imageData = [self newBase64Decode:str];
   UIImage *image = [UIImage imageWithData:imageData];
   return image;
}

//这个可以查看是否是规范的base64，并转成二进制的Data
-(NSData*)newBase64Decode:(NSString *)string
{
    unsigned long ixtext, lentext;
    unsigned char ch, inbuf[4], outbuf[4];
    short i, ixinbuf;
    Boolean flignore, flendtext = false;
    const unsigned char *tempcstring;
    NSMutableData *theData;
    if (string == nil) {
        return [NSData data];
    }
    ixtext = 0;
    tempcstring = (const unsigned char *)[string UTF8String];
    lentext = [string length];
    theData = [NSMutableData dataWithCapacity: lentext];
    ixinbuf = 0;
    while (true) {
        if (ixtext >= lentext){
            break;
        }
        ch = tempcstring [ixtext++];
        flignore = false;
        if ((ch >= 'A') && (ch <= 'Z')) {
            
            ch = ch - 'A';
            
        } else if ((ch >= 'a') && (ch <= 'z')) {
            
            ch = ch - 'a' + 26;
            
        } else if ((ch >= '0') && (ch <= '9')) {
            
            ch = ch - '0' + 52;
            
        } else if (ch == '+') {
            
            ch = 62;
            
        } else if (ch == '=') {
            
            flendtext = true;
            
        } else if (ch == '/') {
            
            ch = 63;
            
        } else {
            flignore = true;
        }
        if (!flignore) {
            
            short ctcharsinbuf = 3;
            
            Boolean flbreak = false;
            
            
            
            if (flendtext) {
                
                if (ixinbuf == 0) {
                    
                    break;
                    
                }
                
                
                
                if ((ixinbuf == 1) || (ixinbuf == 2)) {
                    
                    ctcharsinbuf = 1;
                    
                } else {
                    
                    ctcharsinbuf = 2;
                    
                }
                
                
                
                ixinbuf = 3;
                
                
                
                flbreak = true;
                
            }
            
            
            
            inbuf [ixinbuf++] = ch;
            
            
            
            if (ixinbuf == 4) {
                
                ixinbuf = 0;
                
                
                
                outbuf[0] = (inbuf[0] << 2) | ((inbuf[1] & 0x30) >> 4);
                
                outbuf[1] = ((inbuf[1] & 0x0F) << 4) | ((inbuf[2] & 0x3C) >> 2);
                
                outbuf[2] = ((inbuf[2] & 0x03) << 6) | (inbuf[3] & 0x3F);
                
                
                
                for (i = 0; i < ctcharsinbuf; i++) {
                    
                    [theData appendBytes: &outbuf[i] length: 1];
                    
                }
                
            }
            
            
            
            if (flbreak) {
                
                break;
                
            }
            
        }
        
    }
    
    
    
    return theData;
    
}