Roll forward to cl/333580336

Signed-off-by: Josh Nohle <nohle@google.com>

cpp/platform_v2/impl/ios/condition_variable.h

@@ -0,0 +1,37 @@
+#ifndef PLATFORM_V2_IMPL_IOS_CONDITION_VARIABLE_H_
+#define PLATFORM_V2_IMPL_IOS_CONDITION_VARIABLE_H_
+
+#include "platform_v2/api/condition_variable.h"
+#include "platform_v2/base/exception.h"
+#include "platform_v2/impl/ios/mutex.h"
+#include "absl/synchronization/mutex.h"
+
+namespace location {
+namespace nearby {
+namespace ios {
+
+class ConditionVariable : public api::ConditionVariable {
+ public:
+  explicit ConditionVariable(ios::Mutex* mutex) : mutex_(&mutex->mutex_) {}
+  ~ConditionVariable() override = default;
+
+  Exception Wait() override {
+    cond_var_.Wait(mutex_);
+    return {Exception::kSuccess};
+  }
+  Exception Wait(absl::Duration timeout) override {
+    cond_var_.WaitWithTimeout(mutex_, timeout);
+    return {Exception::kSuccess};
+  }
+  void Notify() override { cond_var_.SignalAll(); }
+
+ private:
+  absl::Mutex* mutex_;
+  absl::CondVar cond_var_;
+};
+
+}  // namespace ios
+}  // namespace nearby
+}  // namespace location
+
+#endif  // PLATFORM_V2_IMPL_IOS_CONDITION_VARIABLE_H_