题目形貌：
app须要在收到MQTT消息的时间震惊30秒和关照栏展示当地关照，一分钟之后移除关照栏消息，这必然涉及到倒计时，出现的题目是当app在配景的时间会出现会出现30秒左右的保活，定时器不走了。。。。。
官网链接：
https://developer.apple.com/documentation/uikit/uiapplication/1623031-beginbackgroundtaskwithexpiratio/
https://developer.apple.com/documentation/backgroundtasks/choosing_background_strategies_for_your_app?language=objc
解决办法：
应用在配景时可以播放声音信息。
可以使用此模式播放无声音乐，App 进入配景后，播放无声音乐，共同beginBackgroundTaskWithName对体系申请配景使用时间，可以使APP在配景长时间保活。
应用提供位置信息 应用场景：在配景时须要不停关照用户位置更新信息。
通过配景一连定位App，可以实现App配景保活。
以下Demo可以实现解决这个题目，但是发现在iOS15以上的体系照旧存在题目。
https://github.com/QiShare/QiAppRunInBackground
https://gitee.com/msmasker/back-runing-demo
解决iOS15以上体系该题目：
https://www.jianshu.com/p/4c02230677f3
以上是Swift写的，改写OC如下：
//// XTBackRunningManager.m// XTBackRunningDemo//// Created by mshi on 2022/1/20.//#import "C2AppBackRunningManager.h"#import <UIKit/UIKit.h>#import <AVFoundation/AVFoundation.h>@interface C2AppBackRunningManager ()@property (nonatomic, strong) AVAudioPlayer *audioPlayer;@property (nonatomic, strong) AVAudioEngine *audioEngine;@property (nonatomic,assign) UIBackgroundTaskIdentifier backgroundTaskIdentifier;@property (nonatomic, strong) NSTimer *applyTimer;@property (nonatomic, strong) NSTimer *taskTimer;@end@implementation C2AppBackRunningManager+ (instancetype)shareManager { static C2AppBackRunningManager *manager = nil; static dispatch_once_t onceToken; dispatch_once(&onceToken, ^{ manager = [[C2AppBackRunningManager alloc] init]; }); return manager;}//- (instancetype)init {// self = [super init];// if (self) {//// [self addNoti];// // 获取定位权限// [self.locationManager requestAlwaysAuthorization];// [self.locationManager requestWhenInUseAuthorization];// }// return self;//}- (void)startBackgroundTask: (UIApplication *)app { self.backgroundTaskIdentifier = [app beginBackgroundTaskWithExpirationHandler:^{ [app endBackgroundTask:self.backgroundTaskIdentifier]; self.backgroundTaskIdentifier = UIBackgroundTaskInvalid; [self applyForMoreTime]; }]; [self.applyTimer invalidate]; self.applyTimer = nil; [self.taskTimer invalidate]; self.taskTimer = nil; self.taskTimer = [NSTimer scheduledTimerWithTimeInterval:5 target:self selector: @selector(doSomething) userInfo:nil repeats:YES];}- (void)stopBackgroundTask { [self.applyTimer invalidate]; self.applyTimer = nil; [self.taskTimer invalidate]; self.taskTimer = nil;}- (void)doSomething { DLog(@"doing some thing: %f", [UIApplication sharedApplication].backgroundTimeRemaining);}- (void)applyForMoreTime { if ([UIApplication sharedApplication].backgroundTimeRemaining < 30) { self.backgroundTaskIdentifier = [[UIApplication sharedApplication] beginBackgroundTaskWithExpirationHandler:^{ [[UIApplication sharedApplication] endBackgroundTask:self.backgroundTaskIdentifier]; self.backgroundTaskIdentifier = UIBackgroundTaskInvalid; [self applyForMoreTime]; }]; NSString *filePath = [[NSBundle mainBundle] pathForResource "Silence" ofType"wav"]; NSURL *fileURL = [[NSURL alloc] initFileURLWithPath:filePath]; if (!fileURL) { NSLog(@"playEmptyAudio 找不到播放文件"); } NSError *error = nil; if (@available(iOS 11.0, *)) { [[AVAudioSession sharedInstance] setCategory:AVAudioSessionCategoryPlayback mode:AVAudioSessionModeDefault routeSharingPolicy:AVAudioSessionRouteSharingPolicyDefault options:AVAudioSessionCategoryOptionMixWithOthers error:&error]; } else { // Fallback on earlier versions [[AVAudioSession sharedInstance] setCategory:AVAudioSessionCategoryPlayback mode:AVAudioSessionModeDefault options:AVAudioSessionCategoryOptionMixWithOthers error:&error]; } // 0.0~1.0,默以为1.0 self.audioPlayer = [[AVAudioPlayer alloc] initWithContentsOfURL:fileURL error:&error]; [self.audioEngine reset]; [self.audioPlayer play]; [self.audioPlayer stop]; }}@end参考链接：
https://www.jianshu.com/p/311d49195d86 |
