Question

我已经以编程方式创建了一个视图，并希望在该视图上添加2个按钮，但在运行应用视图时，其上的按钮不会显示。这是我的示例代码，似乎问题是框架，但如何根据视图框架调整按钮框架：

cv = [[UIView alloc]initWithFrame:CGRectMake(200, 60, 100, 80)];

UIButton *label1 = [[UIButton alloc]initWithFrame:CGRectMake(100,90, 200, 30)]; 
label1=[UIButton buttonWithType:UIButtonTypeRoundedRect]; 
[label1 setTitle: @"Mark as unread" forState: UIControlStateNormal]; 
label1.titleLabel.font=[UIFont fontWithName:@"SegoeUI" size:12.0]; 
[label1 addTarget:self action:@selector(buttonClicked:) forControlEvents:UIControlEventTouchUpInside]; 
label1.backgroundColor=[UIColor blackColor]; 

[cv addSubview:label1]; 

UIButton *label2 = [[UIButton alloc]initWithFrame:CGRectMake(-50,20, 200, 30)]; 
[label2 setTitle: @"Mark as read" forState: UIControlStateNormal]; 
label2=[UIButton buttonWithType:UIButtonTypeRoundedRect]; 
label2.titleLabel.font=[UIFont fontWithName:@"SegoeUI" size:12.0]; 
[label2 addTarget:self action:@selector(nonbuttonClicked:) forControlEvents:UIControlEventTouchUpInside]; 

[cv addSubview:label2];

Answer 1

首先尝试这段代码，我只是删除了buttontype设置行。

UIButton *label1 = [[UIButton alloc]initWithFrame:CGRectMake(0, 0, 100, 30)]; 
//label1=[UIButton buttonWithType:UIButtonTypeRoundedRect];
UIButton *label2 = [[UIButton alloc]initWithFrame:CGRectMake(0, 40, 100, 30)];
//label2=[UIButton buttonWithType:UIButtonTypeRoundedRect];

原因：label1根据第一行中的框架创建，在下一行中，label1将重新分配给由此创建的新按钮实例buttonWithType方法。因此，在已经设置框架的第一个实例中，它被覆盖了。

因此你的代码会变成这样：

cv = [[UIView alloc]initWithFrame:CGRectMake(200, 60, 100, 80)];

UIButton *label1 = [[UIButton alloc]initWithFrame:CGRectMake(0, 0, 100, 30)]; 
[label1 setTitle: @"Mark as unread" forState: UIControlStateNormal]; 
label1.titleLabel.font=[UIFont fontWithName:@"SegoeUI" size:12.0]; 
[label1 addTarget:self action:@selector(buttonClicked:) forControlEvents:UIControlEventTouchUpInside]; 
label1.backgroundColor=[UIColor blackColor]; 

[cv addSubview:label1]; 

UIButton *label2 = [[UIButton alloc]initWithFrame:CGRectMake(0, 40, 100, 30)]; 
[label2 setTitle: @"Mark as read" forState: UIControlStateNormal]; 
label2.titleLabel.font=[UIFont fontWithName:@"SegoeUI" size:12.0]; 
[label2 addTarget:self action:@selector(nonbuttonClicked:) forControlEvents:UIControlEventTouchUpInside]; 

[cv addSubview:label2];

如何以编程方式在UIview上添加UI按钮

1 个答案: