macos - 为什么我的 NSView 委托(delegate)方法没有被调用？

Question

我正在开发我的第一个 Mac 应用程序，但在让我的 NSView 及其委托(delegate)方法正常工作时遇到了一些问题。我有一个 NSViewController 应该响应鼠标事件，即 mouseDown。这不起作用，相反，我创建了一个自定义 NSView 子类，如下所示:

// Delegate method
@protocol CanvasViewDelegate
    - (void)mouseDown:(NSEvent *)event;
@end

@interface CanvasView : NSView
{
    id delegate;
}

@property (nonatomic, strong) id delegate;
@end

@implementation CanvasView
@synthesize delegate;

- (void)mouseDown:(NSEvent *)event
{
    [delegate mouseDown:event];
}

应充当 NSView 委托(delegate)的 NSViewController 相关部分如下所示:

#import "CanvasView.h"

@interface PaintViewController : NSViewController <CanvasViewDelegate>
{
    CanvasView *canvasView;
}

@property (strong) IBOutlet CanvasView *canvasView;

@end 

@synthesize canvasView;

- (id)initWithNibName:(NSString *)nibNameOrNil bundle:(NSBundle *)nibBundleOrNil
    {
        self = [super initWithNibName:nibNameOrNil bundle:nibBundleOrNil];
        if (self) {
        // Initialization code here.
        canvasView = [[CanvasView alloc] init];
        canvasView.delegate = self;
    }

    return self;
}

- (void)mouseDown:(NSEvent *)event
{
    NSLog(@"Down");
}

现在，mouseDown 方法没有被调用，我做错了什么？

Answer 1

如果您希望 NSView 子类接受事件，则必须实现:

 - (BOOL)acceptsFirstResponder {
     return YES;
 }

如记录here .