Question

我有一个设置来在单击另一个按钮时创建UI按钮。一开始看起来一切都很简单，直到我决定创建自己的UI Button类。除了屏幕上没有显示按钮这一事实外，其中大部分都有效。我已经对可能导致它的原因有了一些想法，但让另一双眼睛看代码会很有帮助。

customButton.m

- (id)initWithFrame:(CGRect)frame   //this function was provided
{
    self = [super initWithFrame:frame];
    if (self) {
        //this is stuff I wrote, that could be wrong.
        UIButton* button = [UIButton buttonWithType:UIButtonTypeRoundedRect];
        button.frame = CGRectMake(1,2,100,50);
        [button setTitle:@"Test!" forState:UIControlStateNormal];
        }
   return self;
    NSLog(@"worked?"); //this log is actually outputted! However, if I put this before "return self", it doesn't work. So I'm guessing the problem is with "return self" not being caught.


}

view.m

-(IBAction)createDrawer:(id)sender {
    customButton* newButton = [customButton alloc]; 
    [newButton initWithFrame:newButton.frame]; 
    [self.containerView addSubview:newButton];
    NSLog(@"asdasdadads"); //this actually gets executed, when button is clicked
    }

view.m的第3行发出警告“表达结果未使用”。我猜这与从initWithFrame中没有使用的“返回自我”有关？

Answer 1

是的，确实如此，由于class clusters，您应该真的将init的返回值分配给实例：

customButton *newButton = [[customButton alloc] initWithFrame:f];

此外，传统上类名以大写字母开头。为您的班级CustomButton命名。

修改：另一个问题是，在initWithFrame:方法中，您不会在self上设置属性，而是在另一个实例（button）上设置属性。显然，这不会影响self的状态。

创建一个按钮来制作按钮

1 个答案: