Launch an NSTask and bring it to front

Question

I'm trying to launch another application using NSTask

NSArray* argArray = [NSArray arrayWithObjects:fileName, nil];
NSTask* task = [NSTask launchedTaskWithLaunchPath:appName arguments:argArray];

while this works the main gui window doesn't come to front.

when repeatedly calling with different fileName the new file does get loaded in the app even though only 1 instance of the app is running

any poiners? I did try SetFrontProcess but seems to have no effect even after introducing a delay

I did look into NSRunningApplication but it seems it is not available on 10.5 whereas I need a solution for both 10.5 and 10.6

Answer 1

Don't use NSTask to launch applications. Use NSWorkspace, which has several methods (e.g. -launchApplication:) to launch and activate an application.

Answer 2

If the task you want to launch is a proper application, you can use NSWorkspace's

- (BOOL)openFile:(NSString *)fullPath withApplication:(NSString *)appName
    andDeactivate:(BOOL)flag

Answer 3

To expand on indragie's answer, if you want a new instance launched with a file argument, do something like (untested):

NSDictionary *config = [NSDictionary dictionaryWithObjectsAndKeys:
                         [NSArray arrayWithObject:filePath], NSWorkspaceLaunchConfigurationArguments,
                         nil];
NSError *error = nil;
[[NSWorkspace sharedWorkspace] launchApplicationAtURL:yourAppURL options:NSWorkspaceLaunchNewInstance | NSWorkspaceLaunchDefault configuration:config error:&error]

On 10.5, you might try (not tested):

NSURL *fileURL = [NSURL fileURLWithPath:filePath];
[[NSWorkspace sharedWorkspace] openURLs:[NSArray arrayWithObject:fileURL] withAppBundleIdentifier:@"com.foo.someapp" options:NSWorkspaceLaunchNewInstance | NSWorkspaceLaunchDefault additionalEventParamDescriptor:nil launchIdentifiers:nil];

Answer 4

I grabbed these from my MDFoundationAdditions and MDAppKitAdditions categories.

This solution should work for Mac OS X 10.4.x and later (which is when LSOpenApplication() was introduced):

MDAppKitAdditions.h:

#import <Cocoa/Cocoa.h>
#import "MDFoundationAdditions.h"

@interface NSWorkspace (MDAdditions)
- (BOOL)launchApplicationAtPath:(NSString *)path
          arguments:(NSArray *)argv
            error:(NSError **)error;
@end

MDAppKitAdditions.m:

#import "MDAppKitAdditions.h"
#if MAC_OS_X_VERSION_MIN_REQUIRED <= MAC_OS_X_VERSION_10_4
#include <ApplicationServices/ApplicationServices.h>
#elif MAC_OS_X_VERSION_MIN_REQUIRED >= MAC_OS_X_VERSION_10_5
#include <CoreServices/CoreServices.h>
#endif

@implementation NSWorkspace (MDAdditions)

- (BOOL)launchApplicationAtPath:(NSString *)path arguments:(NSArray *)argv
             error:(NSError **)error {
    BOOL success = YES;
        if (error) *error = nil;

        if (path) {
            FSRef itemRef;
            if ([path getFSRef:&itemRef error:error]) {
                LSApplicationParameters appParameters =
                  {0, kLSLaunchDefaults, &itemRef, NULL, NULL,
                (argv ? (CFArrayRef)argv : NULL), NULL };

                OSStatus status = noErr;
                status = LSOpenApplication(&appParameters, NULL);

                if (status != noErr) {
                    success = NO;
                    NSLog(@"[%@ %@] LSOpenApplication() returned %hi for %@",
                        NSStringFromClass([self class]),
                        NSStringFromSelector(_cmd), status, path);
                    if (error) *error =
        [NSError errorWithDomain:NSOSStatusErrorDomain code:status userInfo:nil];
            }
        }
    }
    return success;
}
@end

MDFoundationAdditions.h:

#import <Foundation/Foundation.h>
#import <CoreServices/CoreServices.h>

@interface NSString (MDAdditions)
- (BOOL)getFSRef:(FSRef *)anFSRef error:(NSError **)anError;
@end

MDFoundationAdditions.h:

#import "MDFoundationAdditions.h"
#import <sys/syslimits.h>

@implementation NSString (MDAdditions)

- (BOOL)getFSRef:(FSRef *)anFSRef error:(NSError **)anError {
    if (anError) *anError = nil;
    OSStatus status = noErr;
    status = FSPathMakeRef((const UInt8 *)[self UTF8String], anFSRef, NULL);
    if (status != noErr) {
        if (anError)
    *anError = [NSError errorWithDomain:NSOSStatusErrorDomain code:status userInfo:nil];
    }
    return (status == noErr);
}
@end