在 Swift 中读取 UIApplicationLaunchOptionsURLKey

只是想阅读 Swift 中的启动选项。

这是我的旧 obj-C 代码，运行良好：

- (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions
{   
    NSURL *URL = [launchOptions valueForKey:UIApplicationLaunchOptionsURLKey];  
    if (URL)

我认为 Swift 代码应该是这样的：

func application(application: UIApplication, didFinishLaunchingWithOptions launchOptions: [NSObject: AnyObject]?) -> Bool
{
    if let options = launchOptions
    {
        let URL: NSURL = options(UIApplicationLaunchOptionsURLKey) as String

但它给出了错误：

'(NSString!) -> $T2' 与 '[NSObject : AnyObject]' 不同

铸造错误？但很难正确地投射它，并且找不到如何做到这一点的链接。

Swift 3:

在斯威夫特 3 中，launchOptions是一个类型的字典[UIApplicationLaunchOptionsKey: Any]?，因此您可以像这样访问该值：

launchOptions?[UIApplicationLaunchOptionsKey.url]

由于密钥类型是UIApplicationLaunchOptionsKey，你可以缩写enum简单地输入.url:

launchOptions?[.url]

与该键关联的值是URL虽然，并且不是String。此外，该键可能不存在于字典中，因此您应该使用条件转换as?而不是普通的铸造。

在 Swift 中，您想要执行以下操作：

func application(_ application: UIApplication, didFinishLaunchingWithOptions launchOptions: [UIApplicationLaunchOptionsKey: Any]?) -> Bool {
    if let url = launchOptions?[.url] as? URL {
        // If we get here, we know launchOptions is not nil, we know
        // key .url was in the launchOptions dictionary, and we know
        // that the type of the launchOptions was correctly identified
        // as URL.  At this point, url has the type URL and is ready to use.
    }

Swift 2:

在你的代码中，launchOptions是一个类型的字典[NSObject: AnyObject]?，因此您需要像这样访问该值：

options?[UIApplicationLaunchOptionsURLKey]

与该键关联的值是NSURL虽然，并且不是String。此外，该键可能不存在于字典中，因此您应该使用条件转换as?而不是普通的铸造。

在 Swift 中，您想要执行以下操作：

func application(application: UIApplication, didFinishLaunchingWithOptions launchOptions: [NSObject: AnyObject]?) -> Bool
{
    if let url = launchOptions?[UIApplicationLaunchOptionsURLKey] as? NSURL {
        // If we get here, we know launchOptions is not nil, we know
        // UIApplicationLaunchOptionsURLKey was in the launchOptions
        // dictionary, and we know that the type of the launchOptions
        // was correctly identified as NSURL.  At this point, url has
        // the type NSURL and is ready to use.
    }