How can I upload PDF by SwiftyDropbox?

I am new to SwiftyDropbox.

I attempted to upload PDF from iOS App.

func uploadPDF(filename: String, fullPath: String){  
    if let data = NSData(contentsOfFile: fullPath){  
    client.filesUpload(path: filename, body: data).response{ response, error in  
    if let metadata = response {  
    println("Uploaded file name: \(metadata.name)")  
    println("Uploaded file revision: \(metadata.rev)")  
    // Get file (or folder) metadata  
    self.client.filesGetMetadata(path: filename).response { response, error in  
    if let metadata = response {  
    println("Name: \(metadata.name)")  
    if let file = metadata as? Files.FileMetadata {  
    println("This is a file.")  
    println("File size: \(file.size)")  
    } else if let folder = metadata as? Files.FolderMetadata {  
    println("This is a folder.")  
    }  
    } else {  
    println(error!)  
    }  
    }  
    } else {  
    println(error!)  
    }  
    }  
    }   
}

However, response is error.

Bad Input: Error in call to API function "files/upload": HTTP header "Dropbox-API-Arg": could not decode input as JSON

What can I do?