目前iOS 13.0以上， 后台常驻时间很短， 一般只有30s时间， 这给用户造成不好的体验。尤其是，你在编辑文章的时，突然来个电话，当你电话结束的时候，你的APP已经被后台kill掉，编辑的文章内容被清空。 当然，你也可以给APP设计草稿箱功能，这个显然会增加你的工作量。所以，后台?；睿啾冉掀鹄此?，一个成本较低的方案。后台保活的方案用的较多有：
1.播放无声音乐
2.请求位置定位
3.Voip
目前我们项目中， 使用的是播放无声音乐，具体项目代码如下：
OFAudioManager.h文件
#import <Foundation/Foundation.h>
NS_ASSUME_NONNULL_BEGIN
@interface OFAudioManager : NSObject
/// 单例
+ (instancetype)sharedIntance;
/// 是否开启后台自动播放无声音乐
@property (nonatomic, assign) BOOL openBackgroundAudioAutoPlay;
@end
NS_ASSUME_NONNULL_END
OFAudioManager.m文件
#import "OFAudioManager.h"
@interface OFAudioManager()<AVAudioPlayerDelegate>
/// 播放会话
@property (nonatomic, strong) AVAudioSession * audioSession;
/// 背景播放器
@property (nonatomic, strong) AVAudioPlayer * backgroundAudioPlayer;
/// 后台运行时间
@property (nonatomic, assign) NSInteger backgroundTimeLength;
/// timer
@property (nonatomic, strong) NSTimer * timer;
@end
@implementation OFAudioManager
// MARK: life cycle
- (void)dealloc{
REMOVE_NOTIFY;
}
#pragma mark --------Notifications--------
+ (instancetype)sharedIntance{
static OFAudioManager *instance = nil;
static dispatch_once_t onceToken;
dispatch_once(&onceToken, ^{
instance = [[OFAudioManager alloc] init];
});
return instance;
}
// MARK: app进入后台
- (void)applicationDidEnterBackground:(NSNotification *)notify{
[self startTimer];
if (self.openBackgroundAudioAutoPlay) {
// 激活会话, 开始播放音乐
[self.audioSession setActive:YES error:NULL];
[self.backgroundAudioPlayer prepareToPlay];
[self.backgroundAudioPlayer play];
}
}
// MARK: app开始进入前台
- (void)applicationDidBecomeActive:(NSNotification *)notify{
// 进入前台,暂停播放音乐
[self removeTimer];
self.backgroundTimeLength = 0;
if (!self.openBackgroundAudioAutoPlay) {
return;
}
[self.backgroundAudioPlayer pause];
[self.audioSession setActive:NO error:nil];
}
// MARK: 声音被打断
- (void)audioSessionInterruption:(NSNotification *)notify{
if (!self.openBackgroundAudioAutoPlay) {
return;
}
NSDictionary *userInfo = notify.userInfo;
if (VALID_DICT(userInfo)) {
NSNumber * interruptionTypeNumber = userInfo[AVAudioSessionInterruptionTypeKey];
if (interruptionTypeNumber) {
AVAudioSessionInterruptionType interruptionType = interruptionTypeNumber.integerValue;
if (interruptionType == AVAudioSessionInterruptionTypeBegan) {
// 中断开始, 音乐被打断
}
else if(interruptionType == AVAudioSessionInterruptionTypeEnded){
// 中断结束, 音乐继续
if (!self.backgroundAudioPlayer.isPlaying) {
[self.audioSession setActive:YES error:NULL];
[self.backgroundAudioPlayer prepareToPlay];
[self.backgroundAudioPlayer play];
}
}
}
}
}
- (instancetype)init{
if (self = [super init]) {
// 设置
self.audioSession = [AVAudioSession sharedInstance];
[self setupListener];
}
return self;
}
// 设置监听者
- (void)setupListener{
REGISTER_NOTIFY(UIApplicationDidEnterBackgroundNotification, @selector(applicationDidEnterBackground:));
REGISTER_NOTIFY(UIApplicationDidBecomeActiveNotification, @selector(applicationDidBecomeActive:));
REGISTER_NOTIFY(AVAudioSessionInterruptionNotification, @selector(audioSessionInterruption:))
}
// MARK: 配置会话
- (void)setupAudioSession{
if ([self.audioSession setCategory:AVAudioSessionCategoryPlayback withOptions:AVAudioSessionCategoryOptionMixWithOthers error:NULL]) {
[self.audioSession setActive:NO error:NULL];
}
}
// MARK: 配置音乐播放器
- (void)setupBackgroundAudioPlayer{
// FIXME: 填写无声音乐的路径
NSString *filePath = [[NSBundle mainBundle] pathForResource:@"silence" ofType:@"mp3"];
NSURL *fileURL = [NSURL fileURLWithPath:filePath];
if (self.backgroundAudioPlayer == nil) {
self.backgroundAudioPlayer = [[AVAudioPlayer alloc] initWithContentsOfURL:fileURL error:NULL];
}
self.backgroundAudioPlayer.numberOfLoops = -1;
self.backgroundAudioPlayer.volume = 1;
self.backgroundAudioPlayer.delegate = self;
}
- (void)setOpenBackgroundAudioAutoPlay:(BOOL)openBackgroundAudioAutoPlay{
_openBackgroundAudioAutoPlay = openBackgroundAudioAutoPlay;
if (openBackgroundAudioAutoPlay) {
// 设置会话
[self setupAudioSession];
// 设置背景播放器
[self setupBackgroundAudioPlayer];
}
else{
// 关闭后台播放音乐
if (self.backgroundAudioPlayer && self.backgroundAudioPlayer.isPlaying) {
[self.backgroundAudioPlayer stop];
}
self.backgroundAudioPlayer = nil;
// 设置激活状态为NO
[self.audioSession setActive:NO withOptions:AVAudioSessionSetActiveOptionNotifyOthersOnDeactivation error:NULL];
}
}
- (void)startTimer{
if (self.timer == nil) {
self.timer = [NSTimer timerWithTimeInterval:1 target:self selector:@selector(timerRun:) userInfo:nil repeats:YES];
[[NSRunLoop currentRunLoop] addTimer:self.timer forMode:NSDefaultRunLoopMode];
}
[self.timer setFireDate:[NSDate distantPast]];
}
- (void)removeTimer{
if (self.timer) {
[self.timer setFireDate:[NSDate distantFuture]];
[self.timer invalidate];
self.timer = nil;
}
}
- (void)timerRun:(NSTimer *)timer{
self.backgroundTimeLength++;
// 超过180秒, 退出播放
if (self.backgroundTimeLength > 180) {
[self stopBackMode];
}
}
// MARK: 退出后台常驻模式
- (void)stopBackMode{
[self removeTimer];
self.backgroundTimeLength = 0;
if (!self.openBackgroundAudioAutoPlay) {
return;
}
[self.backgroundAudioPlayer pause];
[self.audioSession setActive:NO error:nil];
}
#pragma mark --------AVAudioDelegate--------
- (void)audioPlayerDidFinishPlaying:(AVAudioPlayer *)player successfully:(BOOL)flag{
// TODO: 播放完成
}
- (void)audioPlayerDecodeErrorDidOccur:(AVAudioPlayer *)player error:(NSError *)error{
// TODO: 编码类型
}
@end
最后在Appdelegate.m文件中
- (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions {
// 后台播放无声音乐
[OFAudioManager sharedIntance].openBackgroundAudioAutoPlay = YES;
return YES;
}
避免过长时间占用后台资源， 后台停留时间大于180s时，停止播放无声音乐，释放后台任务，提升APP的流程度。
目前测试没有任何问题， 下版提交审核，看苹果爸爸给过不给了??
