drawRect not called with setNeedsDisplay

Question

my ui structure is like NSWindow -> NSViewController -> NSView(parent) -> NSView(target view). the target view is dragged from XIB file, rather than addSubview. The drawRect function will be called when the NSView(parent) is shown, but after that i want to call drawRect again programmatically with setNeedsDisplay, it doesn't work. What's wrong with my method?

Anyway, i can use drawRect(view.frame) to implement this, but i think this is not a good idea.

Code:

MyView.m

- (void)drawRect:(NSRect)dirtyRect {
    [super drawRect:dirtyRect];

    NSLog(@"asasa");
}

...
@property (weak) IBOutlet MyView *titleBarView;
...

-(IBAction)test:(id)sender
{
    NSLog(@"%@",self.view.subviews); // contains the titleBarView
    NSLog(@"%@",self.titleBarView); // not nil
    [self.titleBarView setNeedsDisplay:YES]; // not call drawRect
}

titleBarView is already connected

@bluedome, yes, i called setNeedsDisplay but it doesn't work — jimwan
Show the code which calls setNeedsDisplay:. Also, are you sure you're calling it on the view you think you are? Which view is that, the parent or the target? Could it be that your reference to that view is nil because you didn't connect something (e.g. an outlet) properly? Never call drawRect; it won't work right. — Ken Thomases
i can use [self.view setNeedsDisplay:YES] to call drawRect of the NSView(Parent) — jimwan

Pärserk Pärserk · Accepted Answer · 2016-07-20T06:56:58

What you're doing now will trigger drawRect: of self.titleBarView, but not self.view. To trigger the drawRect: of self.view (the one with the NSLog statement), call setNeedsDisplay on self.view.

- (void)drawRect:(NSRect)dirtyRect {
[super drawRect:dirtyRect];

NSLog(@"asasa");
}

...
@property (weak) IBOutlet MyView *titleBarView;
...

-(IBAction)test:(id)sender
{
    NSLog(@"%@",self.view.subviews); // contains the titleBarView
    NSLog(@"%@",self.titleBarView); // not nil
    [self.titleBarView setNeedsDisplay:YES]; // this triggers the drawRect: method of self.titleBarView
    [self.view setNeedsDisplay:YES]; // this triggers your drawRect: method with he NSLog statement
}

drawRect not called with setNeedsDisplay

1 Answers