Question

当我开始模拟它崩溃时，我试图从firebase检索图像，我得到了这个消息＆＃34; 无法转换类型的值＆＃39; NSNull＆＃39; （0x10eaf2378）到＆＃39; NSString＆＃39; （0x10eee2b20）。＆＃34; 这是我的代码

类ViewController：UIViewController {

@IBOutlet weak var gameName: UILabel!
@IBOutlet weak var videoImage: UIImageView!
@IBOutlet weak var uploadImage: UIButton!


var ref = Firebase(url:"https://xxx.firebaseio.com/images/")
var imageRef = Firebase(url:"https://xxx.firebaseio.com/images/image/string")
var base64String: NSString!

override func viewDidLoad() {
    super.viewDidLoad()
    // Do any additional setup after loading the view, typically from a nib.


    imageRef.observeEventType(.Value, withBlock: { (snapshot) -> Void in

        self.base64String = snapshot.value as? String
        let decodeData = NSData(base64EncodedString: snapshot.value as! String, options: NSDataBase64DecodingOptions())
        let decodeImage = UIImage(data: decodeData!)
        self.videoImage.image = decodeImage
        print(self.base64String)
        }) { (error) -> Void in
            print(error.description)
    }

}

Answer 1

imageRef.observeEventType(.Value, withBlock: { (snapshot) -> Void in

        guard let unwrappedSnapShot = snapshot.value as? String ,
              let decodeData        = NSData(base64EncodedString: unwrappedSnapShot, options: NSDataBase64DecodingOptions())
              else {  /*handle snapshot or decodData was nil*/ return }

         let decodeImage = UIImage(data: decodeData)
         self.videoImage.image = decodeImage
         print(base64String)      
}) { (error) -> Void in
        print(error.description)
}

删除了IUO的使用，你也不应该使用它们你应该把一个捕获列表放在那里以避免保留周期

无法转换类型＆＃39; nsnull＆＃39;到＆＃39; nsstring＆＃39;

1 个答案: