objective-c - Objective-c : action:@selector(xxxxxx) 没有被调用

Question

我目前正在尝试向我的应用程序添加一个按钮。如果用户按下它，它应该显示一个警报。

我想将按钮添加到 a 的部分标题tableview.这是我的代码tableView:viewForHeaderInSection:

UIImageView *headerView = [[[UIImageView alloc] initWithFrame:CGRectMake(0, 0, tableView.bounds.size.width, 20)] autorelease];
...
UIButton *button = [UIButton buttonWithType:UIButtonTypeCustom];
[button setFrame:CGRectMake(180, 4, 15, 15)];
UIImage *img=[UIImage imageNamed:@"myimg"];
[button setImage:img forState:UIControlStateNormal];
[button addTarget:self action:@selector(showMyAlert) forControlEvents:UIControlEventTouchUpInside];
[headerView addSubview:button];
return headerView;

在同一个班级中，我有方法：

-(void)showMyAlert{
    NSLog(@"HERE SHOW ALERT");
    ...
}

该按钮已正确显示，showMyAlert但当我按下它时从未调用该方法。有谁知道我的代码有什么问题？谢谢，如果你能帮助我:)

Answer 1

试试这个，在 viewDidLoad 中，

-(void)viewDidLoad
{
UIView *headerView = [[UIView alloc] initWithFrame:CGRectMake(XXX, YYY, XXX, YYY)];
UIImageView *imageView = [[[UIImageView alloc] initWithFrame:CGRectMake(0, 0, tableView.bounds.size.width, 20)] autorelease];
[headerView addSubview:imageView];
UIButton *button = [UIButton buttonWithType:UIButtonTypeCustom];
[button setFrame:CGRectMake(180, 4, 15, 15)];
UIImage *img=[UIImage imageNamed:@"myimg"];
[button setImage:img forState:UIControlStateNormal];
[button addTarget:self action:@selector(showMyAlert) forControlEvents:UIControlEventTouchUpInside];
[headerView addSubview:button];
self.tableView.tableHeaderView = headerView;
}

Answer 2

确保 img 不为零。如果为 nil，您的按钮将没有图像，您将什么也看不到。

Answer 3

更改您的UIImageViewasUIView并将其作为标题视图返回。

UIView *headerView = [[[UIView alloc] initWithFrame:CGRectMake(0, 0, tableView.bounds.size.width, 20)] autorelease];

Answer 4

修改下面的代码行，试试这样： -

[button addTarget:self action:@selector(showMyAlert:) forControlEvents:UIControlEventTouchUpInside];

-(IBAction)showMyAlert:(id)sender{
    NSLog(@"HERE SHOW ALERT");
    ...
}