iPhone can't execute "SBSLaunchApplicationWithIdentifier"

Question 1

Here is the best way to solve my problem:

%new(v@:@)
-(void)launch:(NSString *)bundle {
    Class SBApplicationController = objc_getClass("SBApplicationController");
    id appController = [SBApplicationController sharedInstance];

    NSArray *apps = [appController applicationsWithBundleIdentifier: bundle];
    if ([apps count] > 0) {
        //Wait .5 seconds.. then launch.
        [self performSelector:@selector(launchTheApp:) withObject:[apps objectAtIndex:0] afterDelay: 0.5];
    } else {
        id app = [appController applicationWithDisplayIdentifier: bundle];
        if (app) {
            //Wait .5 seconds.. then launch.
            [self performSelector:@selector(launchTheApp:) withObject:app afterDelay: 0.5];
        }
    }
}

%new(v@:@)
-(void)launchTheApp:(id)app {
    Class SBUIController = objc_getClass("SBUIController");
    id uiController = [SBUIController sharedInstance];
    if([uiController respondsToSelector:@selector(animateLaunchApplication:)]) {
        [uiController animateLaunchApplication:app animateDefaultImage:YES];
    } else {
        [uiController activateApplicationFromSwitcher:app];
    }
}

Note: activateApplicationFromSwitcher will work better then activateApplicationAnimated

Question 2

Ok, I think I see what's going on here. You are writing a tweak that runs within the SpringBoard application. Normally, the SBSLaunchApplicationWithIdentifier() is probably (?) used to allow other, non-SpringBoard code to open an application, via SpringBoardServices.

In the case of a SpringBoard tweak, the more direct way to launch an app is probably to follow the documentation here ... although I can't test that right now. Here is another Stack Overflow answer that basically uses this technique.

The code you're trying to run does, as the message suggests, require the com.apple.springboard.launchapplications entitlement. Interestingly enough, SpringBoard itself does not have that entitlement, probably because it can just launch apps directly.