Objective-c – Redrawing an NSView

cocoansviewobjective c

Sorry if this has been asked before or it's a really dumb question, but I can't figure it out. I have an NSView in my interface, and I have created a subclass of NSView in Xcode. Then using the identity inspector, I set my NSView's class to be the newly created NSView subclass. The view draws fine, but now I need to redraw it to change a string inside the view. I'm pretty sure this has to do with setNeedsDisplay, but what do I send the message to? I don't have a particular instance of my view in the code, since it's in Interface Builder, so what do I do?
Again, sorry if this is dumb. I haven't done much with NSView yet. Ask for more info if you need it. Thanks!

Best Answer

In the view controller subclass you have, add an ivar with type of your NSView subclass. Declare a property on it, and mark it as an outlet.

// ViewControllerSubclass.h
ViewType *myView;

@property(readwrite, assign) IBOutlet ViewType *myView;

// ViewControllerSubclass.m
@synthesize myView;

Now you have an outlet, connect it to the view you designed via IB. To do so, right click in IB on your view controller subclass (the file's owner), you should see the outlet in the list.

Once you have done that, you are now able to send messages to the view in your code.
To mark the view as needing redraw :

[myView setNeedsDisplay:YES];

Related Solutions

Cocoa – Binding a custom NSView: Does it demand creating an IBPlugin

Answer to title: No, you can bind a custom view without an IB plug-in (by doing it in code).
Answer to question in question body: Yes, you do need an IB plug-in to expose the binding in IB.

Your code doesn't run inside Interface Builder unless you put it into Interface Builder, and that exposeBinding: message is your code. Therefore, you need to put it into Interface Builder. That means writing an IB plug-in.

Also, IB plug-ins are not the same as the old IB palettes. Plug-ins require IB 3 and are much easier to create. Palettes require IB 2 and were painful to create.

Ios – How to make a UITextField move up when the keyboard is present – on starting to edit

You will only need a ScrollView if the contents you have now do not fit in the iPhone screen. (If you are adding the ScrollView as the superview of the components just to make the TextField scroll up when keyboard comes up, then it's not needed.)
The standard way to prevent the TextFields from being covered by the keyboard is to move the view up/down whenever the keyboard is shown.

Here is some sample code:

#define kOFFSET_FOR_KEYBOARD 80.0

-(void)keyboardWillShow {
    // Animate the current view out of the way
    if (self.view.frame.origin.y >= 0)
    {
        [self setViewMovedUp:YES];
    }
    else if (self.view.frame.origin.y < 0)
    {
        [self setViewMovedUp:NO];
    }
}

-(void)keyboardWillHide {
    if (self.view.frame.origin.y >= 0)
    {
        [self setViewMovedUp:YES];
    }
    else if (self.view.frame.origin.y < 0)
    {
        [self setViewMovedUp:NO];
    }
}

-(void)textFieldDidBeginEditing:(UITextField *)sender
{
    if ([sender isEqual:mailTf])
    {
        //move the main view, so that the keyboard does not hide it.
        if  (self.view.frame.origin.y >= 0)
        {
            [self setViewMovedUp:YES];
        }
    }
}

//method to move the view up/down whenever the keyboard is shown/dismissed
-(void)setViewMovedUp:(BOOL)movedUp
{
    [UIView beginAnimations:nil context:NULL];
    [UIView setAnimationDuration:0.3]; // if you want to slide up the view

    CGRect rect = self.view.frame;
    if (movedUp)
    {
        // 1. move the view's origin up so that the text field that will be hidden come above the keyboard 
        // 2. increase the size of the view so that the area behind the keyboard is covered up.
        rect.origin.y -= kOFFSET_FOR_KEYBOARD;
        rect.size.height += kOFFSET_FOR_KEYBOARD;
    }
    else
    {
        // revert back to the normal state.
        rect.origin.y += kOFFSET_FOR_KEYBOARD;
        rect.size.height -= kOFFSET_FOR_KEYBOARD;
    }
    self.view.frame = rect;

    [UIView commitAnimations];
}


- (void)viewWillAppear:(BOOL)animated
{
    [super viewWillAppear:animated];
    // register for keyboard notifications
    [[NSNotificationCenter defaultCenter] addObserver:self
                                         selector:@selector(keyboardWillShow)
                                             name:UIKeyboardWillShowNotification
                                           object:nil];

    [[NSNotificationCenter defaultCenter] addObserver:self
                                         selector:@selector(keyboardWillHide)
                                             name:UIKeyboardWillHideNotification
                                           object:nil];
}

- (void)viewWillDisappear:(BOOL)animated
{
    [super viewWillDisappear:animated];
    // unregister for keyboard notifications while not visible.
    [[NSNotificationCenter defaultCenter] removeObserver:self
                                             name:UIKeyboardWillShowNotification
                                           object:nil];

    [[NSNotificationCenter defaultCenter] removeObserver:self
                                             name:UIKeyboardWillHideNotification
                                           object:nil];
}

Best Answer

Related Solutions

Cocoa – Binding a custom NSView: Does it demand creating an IBPlugin

Ios – How to make a UITextField move up when the keyboard is present – on starting to edit

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