抛出的 Swift2 闭包

Question

我正在尝试创建一个可以抛出的闭包，并将其作为参数传递给另一个函数。例如：

extension NSManagedObjectContext {

  /// The same as performBlockAndWait, except it can handle closures that throw.
  func performBlockAndWaitOrThrow(block: (() -> throws Void)) throws {
    // ...
    try block()
  }
}

注意 |block|参数是一个可以抛出的闭包。

但是，这不会编译。有没有办法做到这一点？

Answer 1

throws 关键字应该出现在箭头之前。这样编译：

extension NSManagedObjectContext {

    /// The same as performBlockAndWait, except it can handle closures that throw.
    func performBlockAndWaitOrThrow(block: (() throws -> Void)) throws {
        // ...
        try block()
    }
}