Question

In my app, a graph in one view can be dragged to a second view so that the new graph replaces the second view (like a copy/paste effect with a drag and drop feature). The app works if the delegate protocol is taken out so that the second view handles the change in function itself. When the protocol is added, the app crashes in the main file at

return UIApplicationMain(argc, argv, nil, NSStringFromClass([Load_CreatorAppDelegate class]));.

There isn’t any error output other than the standard (lldb). Even when I take out the call to the delegate (keeping in the code), the app crashes. I know that it has to be related to the protocol code, though, because it worked fine before that.

Here is part of the code for the second view (BeamView):

[self drawSupportsAtLeftPoint:self.beamBottomLeft rightPoint:self.beamBottomRight inContext:context :leftPin :rightPin];   

BOOL pt = NO;
if (self.tempLoad) {
    //self.loadGraph = [self.dataSource changeToTempLoad:self]; NOTE #1
    //if (self.tempPtLoad.x != 0 || self.tempPtLoad.y != 0) pt = YES;
    pt = [self changeLoad];
    [self drawLoadWithFunction:self.loadGraph inContext:context fromPoint:self.beamTopLeft toPoint:self.beamTopRight withAlpha:0.3 isPointLoad:pt inBlack:YES];
}
else {
    self.loadGraph = ^(int x) {return x/15;};
    [self drawLoadWithFunction:self.loadGraph inContext:context fromPoint:self.beamTopLeft toPoint:self.beamTopRight withAlpha:1 isPointLoad:pt inBlack:NO];
}

self.tempLoad = NO;

NOTE #1: These lines that are commented out are the ones that call on the delegate. Those two methods and their implementation are the only changes I made.

I’m completely confused, any help would be greatly appreciated. What are possible reasons the app will crash in the main file?

Answer 1

Ok! I feel kind of stupid, but it turned out that the crash didn’t have anything to do with delegation (well, kind of). I had deleted outlets in the ViewController.m file without disconnecting them in IB, which was causing the crash.

I’d forgotten that I’d done that, and so it took me a while to think of it–it wasn’t until I went back to an older saved version that I saw the differences.