做越獄應用和插件開發，經常會調用 system 去執行系統命令，早在 Xcode 7，使用 system 函數提示警告：
'system' is deprecated: first deprecated in iOS 8.0 - Use posix_spawn APIs installd
只是警告，還是可以正常編譯和使用，但是升級到 Xcode 9，system 函數就從 SDK 中移除了，不能再使用了，提示：
'system' is unavailable: not available on iOS
替代的方法一般有三種，第一種是使用 posix_spawn，代碼如下：
pid_t pid;
char *argv[] = {
"/bin/ls", //path
"-al", //parameter1
"/", //parameter2
NULL
};
posix_spawn(&pid, argv[0], NULL, NULL, argv, NULL);
printf("pid=%d,child pid = %d\n",getpid(),pid);
int stat;
waitpid(pid,&stat,0);
printf("stat is %d\n",stat);第二種是使用 NSTask，代碼如下：
NSTask *task = [[NSTask alloc] init]; task.launchPath = @"/bin/ls"; task.arguments = [NSArray arrayWithObjects: @"-al", @"/", nil]; [task launch]; [task waitUntilExit];
NSTask.h 頭文件信息如下：
#import <Foundation/NSObject.h>
@class NSString, NSArray, NSDictionary;
@interface NSTask : NSObject
// Create an NSTask which can be run at a later time
// An NSTask can only be run once. Subsequent attempts to
// run an NSTask will raise.
// Upon task death a notification will be sent
// { Name = NSTaskDidTerminateNotification; object = task; }
//
- (instancetype)init;
// set parameters
// these methods can only be done before a launch
// if not set, use current
// if not set, use current
// set standard I/O channels; may be either an NSFileHandle or an NSPipe
- (void)setStandardInput:(id)input;
- (void)setStandardOutput:(id)output;
- (void)setStandardError:(id)error;
// get parameters
@property (NS_NONATOMIC_IOSONLY, copy) NSString *launchPath;
@property (NS_NONATOMIC_IOSONLY, copy) NSArray *arguments;
@property (NS_NONATOMIC_IOSONLY, copy) NSDictionary *environment;
@property (NS_NONATOMIC_IOSONLY, copy) NSString *currentDirectoryPath;
// get standard I/O channels; could be either an NSFileHandle or an NSPipe
- (id)standardInput;
- (id)standardOutput;
- (id)standardError;
// actions
- (void)launch;
- (void)interrupt; // Not always possible. Sends SIGINT.
- (void)terminate; // Not always possible. Sends SIGTERM.
@property (NS_NONATOMIC_IOSONLY, readonly) BOOL suspend;
@property (NS_NONATOMIC_IOSONLY, readonly) BOOL resume;
// status
@property (NS_NONATOMIC_IOSONLY, readonly) int processIdentifier;
@property (NS_NONATOMIC_IOSONLY, getter=isRunning, readonly) BOOL running;
@property (NS_NONATOMIC_IOSONLY, readonly) int terminationStatus;
@end
@interface NSTask (NSTaskConveniences)
+ (NSTask *)launchedTaskWithLaunchPath:(NSString *)path arguments:(NSArray *)arguments;
// convenience; create and launch
- (void)waitUntilExit;
// poll the runLoop in defaultMode until task completes
@end
FOUNDATION_EXPORT NSString * const NSTaskDidTerminateNotification;如果非要調用 system 函數不可，那就使用第三種方法，找到 system 函數地址直接調用，方法參見: 動態調用函數，具體代碼如下：
typedef int (*my_system) (const char *str);
int call_system(const char *str){
//動態庫路徑
char *dylib_path = "/usr/lib/libSystem.dylib";
//打開動態庫
void *handle = dlopen(dylib_path, RTLD_GLOBAL | RTLD_NOW);
if (handle == NULL) {
//打開動態庫出錯
fprintf(stderr, "%s\n", dlerror());
} else {
//獲取 system 地址
my_system system = dlsym(handle, "system");
//地址獲取成功則調用
if (system) {
int ret = system(str);
return ret;
}
dlclose(handle); //關閉句柄
}
return -1;
}這樣 call_system 函數就相當於 system 的功能了，替換即可。