Question

我正在开发我的第一个Mac应用程序，我在使用NSView及其委托方法时遇到了一些麻烦。我有一个应该响应鼠标事件的NSViewController，即mouseDown。这不起作用，而是我创建了一个自定义的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];
}

应该充当NSView委托的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，方法mouseDown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;
 }

记录在案here。

Answer 2

以编程方式创建视图，但确实有效。像这样：

NSRect canvasRect = self.view.frame;
canvasView = [[CanvasView alloc] initWithFrame:canvasRect];
[self.view addSubview:canvasView];
canvasView.delegate = self;

为什么不调用我的NSView委托方法？

2 个答案: