iOS开发 NSTimer 后台运行

来源：互联网发布：傲剑舍利子升级数据编辑：程序博客网时间：2024/06/06 05:09

一般来说当用户点击home键之后 app 会被挂起不会在后台运行今天遇到一个音乐播放器需要在后台倒计时播放时间但是需要NSTimer 再后台也要运行

我的思路是借助 ios 的后台音乐播放

不多说了上代码

首先在pilst 文件里添加 Required background modes 字段添加一项为 App plays audio or streams audio/video using AirPlay

代码中再appdelegate 添加如下代码

#import "AppDelegate.h"

#import "HomeViewController.h"#import <AVFoundation/AVFoundation.h>@implementation AppDelegate- (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions{    self.window = [[UIWindow alloc] initWithFrame:[[UIScreen mainScreen] bounds]];    // Override point for customization after application launch.    self.window.backgroundColor = [UIColor whiteColor];    [self.window makeKeyAndVisible];               //后台执行    NSError *err = nil;    [[AVAudioSession sharedInstance]setCategory: AVAudioSessionCategoryPlayback error: &err];    [[AVAudioSession sharedInstance]setActive: YES error: &err];        return YES;}- (void)applicationDidEnterBackground:(UIApplication *)application{    //设置 后台运行 任务    UIApplication*   app = [UIApplication sharedApplication];    __block    UIBackgroundTaskIdentifier bgTask;    bgTask = [app beginBackgroundTaskWithExpirationHandler:^{        dispatch_async(dispatch_get_main_queue(), ^{            if (bgTask != UIBackgroundTaskInvalid)            {                bgTask = UIBackgroundTaskInvalid;            }        });    }];    dispatch_async(dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0), ^{        dispatch_async(dispatch_get_main_queue(), ^{            if (bgTask != UIBackgroundTaskInvalid)            {                bgTask = UIBackgroundTaskInvalid;            }        });    });}@end

这里设置完成之后 nstimer 就能后台运行了

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