我想从firebase storage ios swift获取图像的下载url

Question

我正在使用firebase上传一些图片，它的工作正常，但问题是我无法获取图片的下载网址

这是我的代码

@IBAction func btnUploadImgsAction(_ sender: UIButton) {


    let url1 = uploading(img: Img1)
    print("///////////img 1   //////// \(url1)   ////////")
    let url2 = uploading(img: Img2)
    print("///////////img 2   //////// \(url2)   ////////")
    let url3 = uploading(img: Img3)
    print("///////////img 3   //////// \(url3)   ////////")
    let url4 = uploading(img: Img4)
    print("///////////img 4   //////// \(url4)   ////////")


}


func uploading( img : UIImageView)-> String{
    var strURL = ""
    let imageName = NSUUID().uuidString
    let storeImage = self.storageRef.child("profile_Images").child(imageName)

    if let uploadImageData = UIImagePNGRepresentation((img.image)!){
        storeImage.putData(uploadImageData, metadata: nil, completion: { (metaData, error) in
            storeImage.downloadURL(completion: { (url, error) in
                if let urlText = url?.absoluteString {

                     strURL = urlText
                    print("///////////tttttttt//////// \(strURL)   ////////")


                }
            })
        })


    }

    return strURL
}

当我在上传方法中打印 strURL 时，url 来了，但是当我在 btnUploadImgsAction 中打印时，它没有来，donig 出了什么问题？ 请帮忙提前谢谢

Answer 1

你应该创建一个闭包方法而不是直接返回字符串的方法，因为这个方法是异步方法

您的方法声明应如下所示

func uploading( img : UIImageView, success: (url: String) -> Void) {
 // return with clouser
 success(url: strurl)
}

用你的方法更新

func uploading( img : UIImageView, completion: @escaping ((String) -> Void)) {
    var strURL = ""
    let imageName = NSUUID().uuidString
    let storeImage = self.storageRef.child("profile_Images").child(imageName)

    if let uploadImageData = UIImagePNGRepresentation((img.image)!){
        storeImage.putData(uploadImageData, metadata: nil, completion: { (metaData, error) in
            storeImage.downloadURL(completion: { (url, error) in
                if let urlText = url?.absoluteString {

                    strURL = urlText
                    print("///////////tttttttt//////// \(strURL)   ////////")

                    completion(strURL)
                }
            })
        })
    }
}

函数调用会是

let str = uploading(img: imageObject) { (url) in
     print(url)
 }