介绍

QAssociativeIterable类是QVariant中一个关联式容器的可迭代接口。这个类允许多种访问在QVariant中保存的关联式容器元素的方法。如果一个QVariant可以转换为QVariantHash或QVariantMap，那么QAssociativeIterable的实例可以从中提取出来。

QHash<int, QString> mapping;
  mapping.insert(7, "Seven");
  mapping.insert(11, "Eleven");
  mapping.insert(42, "Forty-two");

  QVariant variant = QVariant::fromValue(mapping);
  if (variant.canConvert<QVariantHash>()) {
      QAssociativeIterable iterable = variant.value<QAssociativeIterable>();
      // Can use foreach over the values:
      foreach (const QVariant &v, iterable) {
          qDebug() << v;
      }
      // Can use C++11 range-for over the values:
      for (const QVariant &v : iterable) {
          qDebug() << v;
      }
      // Can use iterators:
      QAssociativeIterable::const_iterator it = iterable.begin();
      const QAssociativeIterable::const_iterator end = iterable.end();
      for ( ; it != end; ++it) {
          qDebug() << *it; // The current value
          qDebug() << it.key();
          qDebug() << it.value();
      }
  }

结果：