我在 git hub 上找到了一个条形码扫描仪项目,并将其合并到我的应用程序中 link 。我正在使用 google books API 来获取有关我扫描的图书的信息。
func getBookInfo(isbn: String) {
guard let url = URL(string: "https://www.googleapis.com/books/v1/volumes?q=isbn13:\(isbn)") else {
print("the url is not valid")
return
}
URLSession.shared.dataTask(with: url, completionHandler: {data, response, error -> Void in
guard error == nil else {
print(response)
print(error!.localizedDescription)
return
}
guard let data = data else {
print("no error but no data")
print(response)
return
}
guard let jsonResult = try? JSONSerialization.jsonObject(with: data, options: []) else {
print("the JSON is not valid")
return
}
if let arrayOfTitles = (jsonResult as AnyObject).value(forKeyPath: "items.volumeInfo.title") as? [String] {
self.BookName.text = "\(arrayOfTitles[0])"
print(self.BookName.text!)
}
if let arrayOfAuthors = (jsonResult as AnyObject).value(forKeyPath: "items.volumeInfo.authors") as? [[String]] {
self.Author.text = "\((arrayOfAuthors[0])[0])"
print(self.Author.text!)
}
if let arrayOfCategories = (jsonResult as AnyObject).value(forKeyPath: "items.volumeInfo.categories") as? [[String]] {
self.Category.text = "\((arrayOfCategories[0])[0])"
print(self.Category.text!)
}
if let arrayOfISBN13 = (jsonResult as AnyObject).value(forKeyPath: "items.volumeInfo.industryIdentifiers.identifier") as? [[String]] {
self.ISBN13.text = "\((arrayOfISBN13[0])[0])"
print(self.ISBN13.text!)
}
if let arrayOfISBN10 = (jsonResult as AnyObject).value(forKeyPath: "items.volumeInfo.industryIdentifiers.identifier") as? [[String]] {
self.ISBN10.text = "\((arrayOfISBN10[0])[1])"
print(self.ISBN10.text!)
}
if let arrayOfFormat = (jsonResult as AnyObject).value(forKeyPath: "items.volumeInfo.printType") as? [String] {
self.CoverType.text = "\(arrayOfFormat[0])"
print(self.CoverType.text!)
}
}).resume()
}
在我扫描书籍并收到信息后,我想关闭具有条形码扫描仪的 View Controller ,并在出现的 View Controller 中显示我刚刚扫描的书籍的信息。
extension MultipleImageViewController: BarcodeScannerCodeDelegate {
func barcodeScanner(_ controller: BarcodeScannerController, didCaptureCode code: String, type: String) {
if code.isEmpty {
let delayTime = DispatchTime.now() + Double(Int64(6 * Double(NSEC_PER_SEC))) / Double(NSEC_PER_SEC)
DispatchQueue.main.asyncAfter(deadline: delayTime) {
controller.resetWithError()
}
}
else{
getBookInfo(isbn: code)
let delayTime = DispatchTime.now() + Double(Int64(6 * Double(NSEC_PER_SEC))) / Double(NSEC_PER_SEC)
DispatchQueue.main.asyncAfter(deadline: delayTime) {
controller.dismiss(animated: true, completion: nil)
}
}
}
}
但是,当条形码扫描仪 View Controller 被关闭时,我必须退出应用程序,然后返回应用程序,以便我的信息显示在我想要的 View Controller 中。如果不离开应用程序并返回,我从条形码扫描仪收到的信息不会显示在所需的 View Controller 中。
最佳答案
您的 UI 未更新,因为当 View Controller 已加载而返回时,不会调用方法 viewDidLoad
。相反,为父级创建一个委托(delegate),当您关闭 subview Controller 时将调用该委托(delegate)。有点像这样:
class ParentViewController: UIViewController, BarcodeDelegate {
func presentChildViewController() {
let childViewController = ChildViewController()
childViewController.delegate = self
present(childViewController, animated: true, completion: nil)
}
func dismissedChildViewController(code: String) {
// update UI
}
}
class ChildViewController: UIViewController {
var delegate: BarcodeDelegate?
func dismiss() {
delegate.dismissedChildViewController(code: getCode())
dismiss(animated: true, completion: nil)
}
}
protocol BarcodeDelegate {
func dismissedChildViewController(code: String)
}
很难真正理解问题所在,因此这可能是也可能不是您正在寻找的内容。
关于ios - 发送信息到另一个 View Controller ,我们在Stack Overflow上找到一个类似的问题: https://stackoverflow.com/questions/45385643/