提前退出`CNContactStoreEnumerateContactsHandler`枚举

Question

你怎么早退出CNContactStoreEnumerateContactsHandler的stop被定义为一个布尔值不是一个对象/指针？

var successfulEnumeration = store.EnumerateContacts(fetchRequest, out error, (contact, stop) =>
{
        stop = true; // this does nothing of course  
});

在ObjC/Swift中stop会是这样的UnsafePointer<ObjCBool>,因此:

ObjC: *stop = YES;

ObjC: stop.initialize....

迅速: stop.withUnsafePointer { p in p.memory = true }

Swift2: stop.memory = true

Answer 1

我认为这可能是Xamarin.iOS中的一个错误,如果我们看一下NSSetEnumerator,它的委托签名如下所示:

public delegate Void NSSetEnumerator (NSObject obj, ref Boolean stop)

我认为它需要ref关键字或你设置的值不会改变.

CNContactStoreEnumerateContactsHandler供参考

public delegate Void CNContactStoreEnumerateContactsHandler (CNContact contact,Boolean stop)

我只是要用NSSetEnumerator运行测试,看看它在设置停止时是否停止.

更新 如果您运行下面的代码,您将看到它在达到5时实际停止:

NSSet set = new NSSet<NSNumber> (new []{
    new NSNumber(1),
    new NSNumber(2),
    new NSNumber(3),
    new NSNumber(4),
    new NSNumber(5),
    new NSNumber(6),
    new NSNumber(7),
    new NSNumber(8),
    new NSNumber(9)
});

set.Enumerate ((NSObject obj, ref bool stop) => {

    var num = obj as NSNumber;

    if (num.Int32Value == 5)
        stop = true;
});

可能会发布此错误并立即修复其开源.