前言
一般APP在按下Home键被挂起后,这时APP的 backgroundTimeRemaining 也就是后台运行时间大约只有3分钟,如果在退出APP后,过十几二十二分钟或者更长时间再回到APP,APP就会回到刚打开时的状态,也就是首页;有的项目在被挂起后需要在后台运行一段时间,使有足够的时间来完成与服务器对接的操作,或者需要一直运行的需求;如果需要,则在APP被挂起后,申请后台,来延长后台运行时间。
APP申请后台运行的方式有几种:
播放音乐
定位
Newsstand downloads
fetch 等;
这里主要说下后台播放无声音乐(其实是不播放),采用哪种方式,对应勾选上图;我的项目中有音频播放需求,如果没有,那就找一个播放音频的理由,或者用其他方式实现。
实现
这里采用了两个单例:电话监控(XKTelManager)、后台运行(XKBGRunManager),电话监控可以忽略,视情况而用;采用单例是为了方便管理;
XKTelManager.h
#import <Foundation/Foundation.h>@interface XKTelManager : NSObject///是否在后台运行@property (nonatomic,assign) BOOL inBackgroundRun;+ (XKTelManager *)sharedManager;/** 来电监听 */- (void)startMonitor;@end
XKTelManager.m
#import "XKTelManager.h"#import "XKBGRunManager.h"#import <CoreTelephony/CTCallCenter.h>#import <CoreTelephony/CTCall.h>static XKTelManager *_sharedManger;@interface XKTelManager()@property (nonatomic, strong) CTCallCenter *callCenter;@end@implementation XKTelManager+ (XKTelManager *)sharedManager{ static dispatch_once_t onceTelSingle; dispatch_once(&onceTelSingle, ^{ if (!_sharedManger) { _sharedManger = [[XKTelManager alloc]init]; } }); return _sharedManger;}- (instancetype)init{ self = [super init]; if (self) { _inBackgroundRun = NO; } return self;}#pragma mark -********* 监听电话相关- (void)startMonitor { __weak typeof(self) weakSelf = self; _callCenter = [[CTCallCenter alloc] init]; _callCenter.callEventHandler = ^(CTCall * call) { ///如果已经进入后台了,不做任何操作 if (weakSelf.inBackgroundRun) { return; } ///APP未进入后台 if ([call.callState isEqualToString:CTCallStateDisconnected]){ NSLog(@"电话 --- 断开连接"); [[XKBGRunManager sharedManager] stopBGRun]; } else if ([call.callState isEqualToString:CTCallStateConnected]){ NSLog(@"电话 --- 接通"); } else if ([call.callState isEqualToString:CTCallStateIncoming]){ NSLog(@"电话 --- 待接通"); [[XKBGRunManager sharedManager] startBGRun]; } else if ([call.callState isEqualToString:CTCallStateDialing]){ NSLog(@"电话 --- 拨号中"); [[XKBGRunManager sharedManager] startBGRun]; } else { NSLog(@"电话 --- 无操作"); } };}@end
XKBGRunManager.h
#import <Foundation/Foundation.h>@interface XKBGRunManager : NSObject+ (XKBGRunManager *)sharedManager;/** 开启后台运行 */- (void)startBGRun;/** 关闭后台运行 */- (void)stopBGRun;@end
XKBGRunManager.m
#import "XKBGRunManager.h"///循环时间static NSInteger _circulaDuration = 60;static XKBGRunManager *_sharedManger;@interface XKBGRunManager()@property (nonatomic,assign) UIBackgroundTaskIdentifier task;///后台播放@property (nonatomic,strong) AVAudioPlayer *playerBack;@property (nonatomic, strong) NSTimer *timerAD;///用来打印测试@property (nonatomic, strong) NSTimer *timerLog;@property (nonatomic,assign) NSInteger count;@end@implementation XKBGRunManager{ CFRunLoopRef _runloopRef; dispatch_queue_t _queue;}+ (XKBGRunManager *)sharedManager{ static dispatch_once_t onceRunSingle; dispatch_once(&onceRunSingle, ^{ if (!_sharedManger) { _sharedManger = [[XKBGRunManager alloc]init]; } }); return _sharedManger;}/// 重写init方法,初始化音乐文件- (instancetype)init { if (self = [super init]) { [self setupAudioSession]; _queue = dispatch_queue_create("com.audio.inBackground", NULL); //静音文件 NSString *filePath = [[NSBundle mainBundle] pathForResource:@"****" ofType:@"mp3"]; NSURL *fileURL = [[NSURL alloc] initFileURLWithPath:filePath]; self.playerBack = [[AVAudioPlayer alloc] initWithContentsOfURL:fileURL error:nil]; [self.playerBack prepareToPlay]; // 0.0~1.0,默认为1.0 self.playerBack.volume = 0.01; // 循环播放 self.playerBack.numberOfLoops = -1; } return self;}- (void)setupAudioSession { // 新建AudioSession会话 AVAudioSession *audioSession = [AVAudioSession sharedInstance]; // 设置后台播放 NSError *error = nil; [audioSession setCategory:AVAudioSessionCategoryPlayback withOptions:AVAudioSessionCategoryOptionMixWithOthers error:&error]; if (error) { NSLog(@"Error setCategory AVAudioSession: %@", error); } NSLog(@"%d", audioSession.isOtherAudioPlaying); NSError *activeSetError = nil; // 启动AudioSession,如果一个前台app正在播放音频则可能会启动失败 [audioSession setActive:YES error:&activeSetError]; if (activeSetError) { NSLog(@"Error activating AVAudioSession: %@", activeSetError); }}/** 启动后台运行 */- (void)startBGRun{ [self.playerBack play]; [self applyforBackgroundTask]; ///确保两个定时器同时进行 dispatch_async(_queue, ^{ self.timerLog = [[NSTimer alloc] initWithFireDate:[NSDate date] interval:1 target:self selector:@selector(log) userInfo:nil repeats:YES]; self.timerAD = [[NSTimer alloc] initWithFireDate:[NSDate date] interval:_circulaDuration target:self selector:@selector(startAudioPlay) userInfo:nil repeats:YES]; _runloopRef = CFRunLoopGetCurrent(); [[NSRunLoop currentRunLoop] addTimer:self.timerAD forMode:NSDefaultRunLoopMode]; [[NSRunLoop currentRunLoop] addTimer:self.timerLog forMode:NSDefaultRunLoopMode]; CFRunLoopRun(); });}/** 申请后台 */- (void)applyforBackgroundTask{ _task =[[UIApplication sharedApplication] beginBackgroundTaskWithExpirationHandler:^{ dispatch_async(dispatch_get_main_queue(), ^{ [[UIApplication sharedApplication] endBackgroundTask:_task]; _task = UIBackgroundTaskInvalid; }); }];}/** 打印 */- (void)log{ _count = _count + 1; NSLog(@"_count = %ld",_count)}/** 检测后台运行时间 */- (void)startAudioPlay{ _count = 0; dispatch_async(dispatch_get_main_queue(), ^{ if ([[UIApplication sharedApplication] backgroundTimeRemaining] < 61.0) { NSLog(@"后台快被杀死了"); [self.playerBack play]; [self applyforBackgroundTask]; } else{ NSLog(@"后台继续活跃呢"); }///再次执行播放器停止,后台一直不会播放音乐文件 [self.playerBack stop]; });}/** 停止后台运行 */- (void)stopBGRun{ if (self.timerAD) { CFRunLoopStop(_runloopRef); [self.timerLog invalidate]; self.timerLog = nil; // 关闭定时器即可 [self.timerAD invalidate]; self.timerAD = nil; [self.playerBack stop]; } if (_task) { [[UIApplication sharedApplication] endBackgroundTask:_task]; _task = UIBackgroundTaskInvalid; }}@end
最后在 AppDelegate.m 对应的方法中,实现开启和停止后台运行即可!
以上就是本文的全部内容,希望对大家的学习有所帮助,也希望大家多多支持武林网。
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