swift 2 : Catching errors in a closure

Question

我有以下代码，它使用闭包延迟初始化属性:

lazy var persistentStoreCoordinator: NSPersistentStoreCoordinator = {
    let coordinator = NSPersistentStoreCoordinator(managedObjectModel: self.managedObjectModel)
    do {
        try coordinator.addPersistentStoreWithType(NSInMemoryStoreType, configuration: nil, URL: nil, options: nil)
    } catch let err as NSError {
        XCTFail("error creating store: \(err)")
    }
    return coordinator

}()

编写的代码产生错误:

Call can throw, but it is not marked with 'try' and the error is not handled

代码标有'try'，错误被处理。当我将闭包移动到一个单独的函数中并在此处调用它时，一切都按预期进行。

关于闭包和 do/try/catch 有什么我不明白的，或者我遇到过(又一个!)美妙的 Swift 2 编译器中的错误？

Answer 1

问题是你的 catch 没有捕获所有可能的异常，所以闭包仍然可以抛出。使用通用捕获:

lazy var persistentStoreCoordinator: NSPersistentStoreCoordinator = {
    let coordinator = NSPersistentStoreCoordinator(managedObjectModel:  self.managedObjectModel)
    do {
        try coordinator.addPersistentStoreWithType(NSInMemoryStoreType, configuration: nil, URL: nil, options: nil)
    } catch {
        XCTFail("error creating store: \(error)")
    }
    return coordinator
}()