ios - 如何通过应用程序ID确定iOS上哪些应用程序是后台应用程序，哪些应用程序是前台应用程序

Question

使用 this question 中描述的方法，我可以获得在 iOS 设备上运行的应用程序列表。我知道 PID 并且可以访问它们的 kinfo_proc 结构。如何确定哪些是前台进程哪些是后台进程(假设我的应用程序是后台进程)？

我试图根据 kinfo_proc 中的信息(参见第一个链接)通过 kp_proc.p_priority 找到它，但似乎无法推断出背景/优先级的前景状态。

我真的不在乎这是否适用于 AppStore Review，但我更喜欢一种无需越狱即可工作的方法(即私有(private) API 可以，但哪些？)。我希望它至少能在 iOS 5 上运行

我考虑过编写一个简单的 MobileSubstrate 扩展，将其注入(inject)所有应用程序并 Hook 每个人的 applicationDidBecomeActive，但这需要越狱并且侵入性太大。

Answer 1

好吧，看起来 nm 和 IDA 在模拟器的 SpringBoardServices 二进制文件上的一些用法在这方面帮助了我。以下代码适用于在 iPod Touch 4、iPhone 4 和 iPad1 WiFi(所有非 JB)上运行的 iOS 5.0.1当然，您永远不应该尝试将其提交给 AppStore

- (NSArray*) getActiveApps
{
mach_port_t *p;
void *uikit = dlopen(UIKITPATH, RTLD_LAZY);
int (*SBSSpringBoardServerPort)() = 
dlsym(uikit, "SBSSpringBoardServerPort");
p = (mach_port_t *)SBSSpringBoardServerPort(); 
dlclose(uikit);

void *sbserv = dlopen(SBSERVPATH, RTLD_LAZY);
NSArray* (*SBSCopyApplicationDisplayIdentifiers)(mach_port_t* port, BOOL runningApps,BOOL debuggable) = 
dlsym(sbserv, "SBSCopyApplicationDisplayIdentifiers");
//SBDisplayIdentifierForPID - protype assumed,verification of params done
void* (*SBDisplayIdentifierForPID)(mach_port_t* port, int pid,char * result) = 
dlsym(sbserv, "SBDisplayIdentifierForPID");
//SBFrontmostApplicationDisplayIdentifier - prototype assumed,verification of params done,don't call this TOO often(every second on iPod touch 4G is 'too often,every 5 seconds is not)
void* (*SBFrontmostApplicationDisplayIdentifier)(mach_port_t* port,char * result) = 
dlsym(sbserv, "SBFrontmostApplicationDisplayIdentifier");



//Get frontmost application
char frontmostAppS[256];
memset(frontmostAppS,sizeof(frontmostAppS),0);
SBFrontmostApplicationDisplayIdentifier(p,frontmostAppS);
NSString * frontmostApp=[NSString stringWithFormat:@"%s",frontmostAppS];
//NSLog(@"Frontmost app is %@",frontmostApp);
//get list of running apps from SpringBoard
NSArray *allApplications = SBSCopyApplicationDisplayIdentifiers(p,NO, NO);
//Really returns ACTIVE applications(from multitasking bar)
/*   NSLog(@"Active applications:");
 for(NSString *identifier in allApplications) {
 // NSString * locName=SBSCopyLocalizedApplicationNameForDisplayIdentifier(p,identifier);
 NSLog(@"Active Application:%@",identifier);
 }
 */ 

//get list of all apps from kernel
int mib[4] = {CTL_KERN, KERN_PROC, KERN_PROC_ALL, 0};
size_t miblen = 4;

size_t size;
int st = sysctl(mib, miblen, NULL, &size, NULL, 0);

struct kinfo_proc * process = NULL;
struct kinfo_proc * newprocess = NULL;

do {

    size += size / 10;
    newprocess = realloc(process, size);

    if (!newprocess){

        if (process){
            free(process);
        }

        return nil;
    }

    process = newprocess;
    st = sysctl(mib, miblen, process, &size, NULL, 0);

} while (st == -1 && errno == ENOMEM);

if (st == 0){

    if (size % sizeof(struct kinfo_proc) == 0){
        int nprocess = size / sizeof(struct kinfo_proc);

        if (nprocess){

            NSMutableArray * array = [[NSMutableArray alloc] init];

            for (int i = nprocess - 1; i >= 0; i--){

                int ruid=process[i].kp_eproc.e_pcred.p_ruid;
                int uid=process[i].kp_eproc.e_ucred.cr_uid;
                //short int nice=process[i].kp_proc.p_nice;
                //short int u_prio=process[i].kp_proc.p_usrpri;
                short int prio=process[i].kp_proc.p_priority;
                NSString * processID = [[NSString alloc] initWithFormat:@"%d", process[i].kp_proc.p_pid];
                NSString * processName = [[NSString alloc] initWithFormat:@"%s", process[i].kp_proc.p_comm];


                BOOL systemProcess=YES;
                if (ruid==501)
                    systemProcess=NO;



                char * appid[256];
                memset(appid,sizeof(appid),0);
                int intID,intID2;
                intID=process[i].kp_proc.p_pid,appid;
                SBDisplayIdentifierForPID(p,intID,appid);/

                NSString * appId=[NSString stringWithFormat:@"%s",appid];

                if (systemProcess==NO)
                {
                    if ([appId isEqualToString:@""])
                    {
                        //final check.if no appid this is not springboard app
                        NSLog(@"(potentially system)Found process with PID:%@ name %@,isSystem:%d,Priority:%d",processID,processName,systemProcess,prio);
                    }
                    else
                    {

                        BOOL isFrontmost=NO;
                        if ([frontmostApp isEqualToString:appId])
                        {
                            isFrontmost=YES;
                        }
                        NSNumber *isFrontmostN=[NSNumber numberWithBool:isFrontmost];
                        NSDictionary * dict = [[NSDictionary alloc] initWithObjects:[NSArray arrayWithObjects:processID, processName,appId,isFrontmostN, nil] 
                                                                            forKeys:[NSArray arrayWithObjects:@"ProcessID", @"ProcessName",@"AppID",@"isFrontmost", nil]];

                        NSLog(@"PID:%@, name: %@, AppID:%@,isFrontmost:%d",processID,processName,appId,isFrontmost);
                        [array addObject:dict];
                    }
                }
            }

            free(process);
            return array;
        }
    }
  }

    dlclose(sbserv);
}

当然，第二个循环并不是绝对必要的，但我也需要非本地化的名称和 PID。