Question

我有以下法典,在ool之后,我想补充一下我的想法。这里是我所持有的法典,但出于某种原因,它不是设置ool子,也不是称呼 set。我要适当提及其他类别? 感谢

页: 1 页: 1

-(IBAction)colorToggle:(id)sender
{
    if ([colorFilter state] == NSOnState) 
    {
        CutoutView *theView = [[CutoutView alloc] init];
        [theView setFilterEnabled:YES];

    iii

iii

//in cutoutView.m

- (void)drawRect:(NSRect)dirtyRect
{
    [[[NSColor blackColor]colorWithAlphaComponent:0.9]set];
    NSRectFill(dirtyRect); 

    //this is what i want to be drawn when my bool is true and update the drawRect        
    if (filterEnabled == YES) {
        NSRectFillUsingOperation(NSMakeRect(100, 100, 300, 300), NSCompositeClear);
        [self update];
    iii
iii

-(void)update
{
    [self setNeedsDisplay:YES];
iii

Answer 1

OK, you know how not every UILabel is the same? Like, you can remove one UILabel from a view without all the others disappearing too? Well, your CutoutView is the same way. When you write CutoutView *theView = [[CutoutView alloc] init]; there, that creates a new CutoutView that isn t displayed anywhere. You need to talk to your existing CutoutView (probably by hooking up an outlet, but there are any number of perfectly valid designs that will accomplish this goal).

Answer 2

页: 1 这种方法应当着眼于:

CutoutView *theView = [[CutoutView alloc] init];
[theView setFilterEnabled:YES];
[theView setNeedsDisplay];

From the docs:

When the actual content of your view changes, it is your responsibility to notify the system that your view needs to be redrawn. You do this by calling your view’s setNeedsDisplay or setNeedsDisplayInRect: method of the view.

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