1. 技术文章
  2. how to determine which apps are background and which app is foreground on iOS by application id

how to determine which apps are background and which app is foreground on iOS by application id

由 不羁的心 提交于 2019-11-26 03:37:47

问题


Using the method described in this question, I can get a list of apps running on an iOS device. I know PIDs and have access to their kinfo_proc structures. How can I determine which are foreground processes and which are background (assuming my app is background)?

I tried to find this out base on information in kinfo_proc (see 1st link), via kp_proc.p_priority, but it looks like it is not possible to infer background/foreground state from priority.

I don\'t really care if this works correctly for AppStore Review but I would prefer a method that will work without a jailbreak(i.e. Private APIs are ok but which ones?). I want this to work at least on iOS 5

I considered writing a simple MobileSubstrate extension, injecting it into all apps and just hook everyone\'s applicationDidBecomeActive, but this requires a jailbreak and is too invasive.


回答1:


Well, looks like some usage of nm and IDA on SpringBoardServices binary from simulator helped me on this. Following code works on iOS 5.0.1 running on iPod Touch 4, iPhone 4 and iPad1 WiFi(all non-JB) Of course you should never try to submit that to 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);
}

Of course 2nd loop is not strictly necessary but I needed non-localized names & PIDs too.




回答2:


Great answer! But there is a small typo in your code, it should be:

First make sure that SBSERVPATH is defined and the correct header files are included:

#import <sys/sysctl.h>
#import <dlfcn.h>

#define SBSERVPATH "/System/Library/PrivateFrameworks/SpringBoardServices.framework/SpringBoardServices"

Then first find the correct SB port:

mach_port_t *port;
void *lib = dlopen(SBSERVPATH, RTLD_LAZY);
int (*SBSSpringBoardServerPort)() = 
dlsym(lib, "SBSSpringBoardServerPort");
port = (mach_port_t *)SBSSpringBoardServerPort(); 
dlclose(lib);

And then find the active app:

mach_port_t * port = [self getSpringBoardPort];
// open springboard lib
void *lib = dlopen(SBSERVPATH, RTLD_LAZY);

// retrieve function SBFrontmostApplicationDisplayIdentifier
void *(*SBFrontmostApplicationDisplayIdentifier)(mach_port_t *port, char *result) =
dlsym(lib, "SBFrontmostApplicationDisplayIdentifier");

// reserve memory for name
char appId[256];
memset(appId, 0, sizeof(appId));

// retrieve front app name
SBFrontmostApplicationDisplayIdentifier(port, appId);

// close dynlib
dlclose(lib);



回答3:


This is what works for me on all IOS devices:

#define UIKITPATH "/System/Library/Framework/UIKit.framework/UIKit"
#define SBSERVPATH "/System/Library/PrivateFrameworks/SpringBoardServices.framework/SpringBoardServices"

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

if(self.frameWorkPath == nil || self.frameWorkPath.length == 0)
{
    self.frameWorkPath = @SBSERVPATH;
    self.frameWorkPath = [self.frameWorkPath stringByTrimmingCharactersInSet:[NSCharacterSet newlineCharacterSet]];
}

const char *cString = [self.frameWorkPath cStringUsingEncoding:NSUTF8StringEncoding];
//const char *bar = [self.frameWorkPath UTF8String];
void *sbserv = dlopen(cString, 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[512];
memset(frontmostAppS,sizeof(frontmostAppS),0);
SBFrontmostApplicationDisplayIdentifier(p,frontmostAppS);
NSString * frontmostApp=[NSString stringWithFormat:@"%s",frontmostAppS];

if([self iOsMajorVersion] >= 7){
    NSNumber *topmost = [NSNumber numberWithBool:YES];
    NSMutableDictionary * dict = [[NSMutableDictionary alloc] init];
    NSMutableArray  * splitted = [frontmostApp componentsSeparatedByString:@"."];
    if(frontmostApp.length > 0 && splitted != nil && splitted.count > 1 && topmost.boolValue == YES){
        NSString *appname = [splitted lastObject];
        [dict setObject:[appname capitalizedString] forKey:@"ProcessName"];
        [dict setObject:frontmostApp forKey:@"ProcessID"];
        [dict setObject:frontmostApp forKey:@"AppID"];
        [dict setObject:topmost forKey:@"isFrontmost"];
        NSLog(@"Running TOPMOST App %@",dict);
        return @[dict];
    }
    else{
        return nil;
    }
}
//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);
 }


来源：https://stackoverflow.com/questions/8252396/how-to-determine-which-apps-are-background-and-which-app-is-foreground-on-ios-by

标签
ios
iphone-privateapi
易学教程内所有资源均来自网络或用户发布的内容，如有违反法律规定的内容欢迎反馈！
该文章没有解决你所遇到的问题?点击提问,说说你的问题,让更多的人一起探讨吧!