Erlo

iOS实现后台长时间运行

时间:2018-10-13 00:00   阅读:43次   来源:脚本之家页面报错

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;
#zs#*
 来电监听
 #fzs#
- (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;

#zs#*
 开启后台运行
 #fzs#
- (void)startBGRun;

#zs#*
 关闭后台运行
 #fzs#
- (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);
  }
}

#zs#*
 启动后台运行
 #fzs#
- (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();
  });
}

#zs#*
 申请后台
 #fzs#
- (void)applyforBackgroundTask{
  _task =[[UIApplication sharedApplication] beginBackgroundTaskWithExpirationHandler:^{
    dispatch_async(dispatch_get_main_queue(), ^{
      [[UIApplication sharedApplication] endBackgroundTask:_task];
      _task = UIBackgroundTaskInvalid;
    });
  }];
}

#zs#*
 打印
 #fzs#
- (void)log{
  _count = _count + 1;
  NSLog(@"_count = %ld",_count)
}

#zs#*
 检测后台运行时间
 #fzs#
- (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];
  });
}

#zs#*
 停止后台运行
 #fzs#
- (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脚本之家。

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