C API注册回调时，iphone应用程序将进入后台

Question

我有一个小的c库，当应用程序进入后台时，它需要进行一些清理。我怎么能在C/C++中做到这一点呢。在Objective-C和swift中，似乎有注册回调的方法。

iOS13或更高版本

UIScene.willDeactivateNotification

iOS12或更早版本

UIApplication.willResignActiveNotification

[1]https://stackoverflow.com/a/34745677/811335

[2]https://developer.apple.com/documentation/uikit/uiapplicationdelegate/1622997-applicationdidenterbackground

Answer 1

基于此处的CFNotificationCenter示例https://stackoverflow.com/a/6969178/5329717

#include <CoreFoundation/CoreFoundation.h>
#include <UIKit/UIApplication.h>
void uiApplicationWillResignNotificationCallback (CFNotificationCenterRef center,
void * observer,
CFStringRef name,
const void * object,
CFDictionaryRef userInfo) {
CFShow(CFSTR("Received uiApplicationWillResignNotification"));
}
void exampleHandling() {
CFNotificationCenterRef center = CFNotificationCenterGetLocalCenter();
// add an observer
CFNotificationCenterAddObserver(center, NULL, uiApplicationWillResignNotificationCallback,
(__bridge CFStringRef)UIApplicationWillResignActiveNotification, NULL,
CFNotificationSuspensionBehaviorDeliverImmediately);

//remove observer
CFNotificationCenterRemoveObserver(center, uiApplicationWillResignNotificationCallback, (__bridge CFStringRef)UIApplicationWillResignActiveNotification, NULL);
}