就這麼簡單。有可能知道一個字符串是否在base64中編碼?
我正在製作一個應用程序,用戶必須掃描一個QR碼(基本上是一個base64編碼的字符串),有沒有什麼方法可以驗證該字符串是在base64編碼之前解碼並遵循流程應用?
我的代碼將負責是:
func captureOutput(captureOutput: AVCaptureOutput!, didOutputMetadataObjects metadataObjects: [AnyObject]!, fromConnection connection: AVCaptureConnection!) {
if metadataObjects == nil || metadataObjects.count == 0 {
qrCodeFrameView?.frame = CGRectZero
return
}
let metadataObj = metadataObjects[0] as AVMetadataMachineReadableCodeObject
if metadataObj.type == AVMetadataObjectTypeQRCode {
let barCodeObject = videoPreviewLayer?.transformedMetadataObjectForMetadataObject(metadataObj as AVMetadataMachineReadableCodeObject) as AVMetadataMachineReadableCodeObject
qrCodeFrameView?.frame = barCodeObject.bounds
if metadataObj.stringValue != nil /* Verify that string is base 64 before continue */ {
let decodedData = NSData(base64EncodedString: metadataObj.stringValue, options: NSDataBase64DecodingOptions.IgnoreUnknownCharacters)
let decodedString = NSString(data: decodedData!, encoding: NSUTF8StringEncoding)
println(decodedString)
}
/* More code */
}
}