Xcode 6 + iOS 8 SDK，但在iOS 7上部署（UIWebKit& WKWebKit） [英] Xcode 6 + iOS 8 SDK but deploy on iOS 7 (UIWebKit & WKWebKit)

问题描述

我们正在iOS 8 SDK上使用Xcode 6 beta 5 + Swift创建一个应用程序。我们也想部署到iOS 7。那可能吗？当我们将项目的部署目标设置为7.0时，我们得到如下编译时错误：

We are creating an app using Xcode 6 beta 5 + Swift on iOS 8 SDK. We'd like to deploy to iOS 7 as well. Is that possible? When we set the deployment target of the project to 7.0, we get compile time errors like this:

Undefined symbols for architecture x86_64:
  "_OBJC_CLASS_$_WKPreferences", referenced from:
      __TMaCSo13WKPreferences in WebViewController.o
  "_OBJC_CLASS_$_WKWebView", referenced from:
      __TMaCSo9WKWebView in WebViewController.o
  "_OBJC_CLASS_$_WKWebViewConfiguration", referenced from:
      __TMaCSo22WKWebViewConfiguration in WebViewController.o
ld: symbol(s) not found for architecture x86_64
clang: error: linker command failed with exit code 1 (use -v to see invocation)

我相信这是因为我们正在使用 WKWebKit ，仅受iOS 8+支持。对于iOS 7，我们可以使用 UIWebKit ，但对于iOS 8，我们可以使用 WKWebKit 。我们如何定义它？

I believe that's because we are using WKWebKit, which is supported by iOS 8+ only. We are ok with using UIWebKit for iOS 7 but WKWebKit for iOS 8. How do we define that?

我们的类定义如下所示......

Our class definition looks like this...

import WebKit

class WebViewController: UIViewController, WKNavigationDelegate {
   ...
}

并且它被调用：

        let mainStoryboard = UIStoryboard(name: "Main", bundle: nil)
        let destinationVC = mainStoryboard.instantiateViewControllerWithIdentifier("WebViewController") as WebViewController
        presentViewController(destinationVC, animated: true, completion: nil)

我在考虑使用这个片段调用 presentViewController ，但这并不能解决编译时的问题。 （ NSFoundationVersionNumber 也不能解决编译时问题）

I was thinking about using this fragment to call presentViewController but that doesn't solve the compile time issues. (NSFoundationVersionNumber doesn't solve compile time issues either)

    if ((UIDevice.currentDevice().systemVersion as NSString).floatValue >= 8.0) {

    } else {

    }

更新：kkoltzau有正确的答案。我正在为其他人添加更多信息。

首先，转到项目，点击在常规上，向下滚动到链接的框架和库，并添加 WebKit.framework 作为可选。 （我也是为 UIKit.framework 做的）见截图：

First, go to your Project, click on General, scroll down to Linked Frameworks and Libraries, and add WebKit.framework as Optional. (I also did it for UIKit.framework) See screenshot:

至于我的 WebViewController 上课。它仍然导入 UIKit 和 WebKit 。但 viewDidLoad（）根据kkoltzau的例子设置视图。然后每当我需要加载/重新加载网页时，它会检查是否存在 wkWebView 。

As for my WebViewController class. It still imports UIKit and WebKit. but the viewDidLoad() sets the view based on kkoltzau's example. Then whenever I need to load/reload the web page, it checks for existence of wkWebView.

推荐答案

您将需要检查WKWebView是否可用，如果不是，则返回UIWebView。

You will need to check if WKWebView is available, and fall back to UIWebView if its not.

确保您链接WebKit.framework（设置为可选）

Make sure you weak link WebKit.framework (set to optional)

Objective-C：

Objective-C:

WKWebView *wkWebView = nil;
UIWebView *uiWebView = nil;

Class wkWebViewClass = NSClassFromString(@"WKWebView");
if(wkWebViewClass) {
    WKWebViewConfiguration *config = [[WKWebViewConfiguration alloc] init];
    // ...
    wkWebView = [[wkWebViewClass alloc] initWithFrame:frame configuration:config];
    [self.view addSubview:wkWebView];
}
else {
    uiWebView = [[UIWebView alloc] initWithFrame:frame];
    [self.view addSubview:uiWebView];
}

Swift：

var wkWebView : WKWebView?
var uiWebView : UIWebView?

if NSClassFromString("WKWebView") {
    let config = WKWebViewConfiguration()
    // ...
    wkWebView = WKWebView(frame: frame, configuration: config)
    self.view.addSubview(wkWebView)
}
else {
    uiWebView = UIWebView(frame: frame)
    self.view.addSubview(uiWebView)
}

然后代码中的其他地方：

Then elsewhere in your code:

Objective-C：

Objective-C:

if(wkWebView) {
    // WKWebView specific code
}
else {
    // UIWebView specific code
}

Swift ：

if let w=wkWebView {
    // WKWebView specific code
}
else if let w=uiWebView {
    // UIWebView specific code
}

这篇关于Xcode 6 + iOS 8 SDK，但在iOS 7上部署（UIWebKit& WKWebKit）的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！