使用 UIPickerView 初始化 UIButton 并将其放置在 UIActionSheet 中

Question

我正在通过 添加 UIPickerView & 来实现选择器操作表中的按钮 - 如何？。我尝试用 UIButton 替换 UISegmentedControl 但它不起作用。有人能提醒我为什么 UIButton 不能在这里显示吗？

谢谢。

- (IBAction) makeButtonPressed: (id) sender;
{
    UIActionSheet *actionSheet = [[UIActionSheet alloc] init];
    [actionSheet setTitle:@"Select Make"];
    [actionSheet setActionSheetStyle:UIActionSheetStyleBlackOpaque];

    UIPickerView *pickerView = [[UIPickerView alloc] initWithFrame:CGRectMake(0, 44, 0, 0)];
    pickerView.dataSource = self;
    pickerView.delegate = self;
    pickerView.showsSelectionIndicator = YES;
    [actionSheet addSubview:pickerView];

//  UISegmentedControl *doneButton = [[UISegmentedControl alloc] initWithItems:[NSArray arrayWithObject:@"Done"]];
//  doneButton.momentary = YES; 
//  doneButton.frame = CGRectMake(260, 7.0f, 50.0f, 30.0f);
//  doneButton.segmentedControlStyle = UISegmentedControlStyleBar;
//  doneButton.tintColor = [UIColor blackColor];
//  [doneButton addTarget:self action:@selector(makeDone:) forControlEvents:UIControlEventValueChanged];
//  [actionSheet addSubview:doneButton];

    UIButton *doneButton = [[UIButton alloc] init];
    doneButton.frame = CGRectMake(260, 7.0f, 50.0f, 30.0f);
    [doneButton addTarget:self action:@selector(makeDone:) forControlEvents:UIControlEventValueChanged];
    [actionSheet addSubview:doneButton];

    [actionSheet showInView:[[UIApplication sharedApplication] keyWindow]];

    [actionSheet setBounds:CGRectMake(0, 0, 320, 460)];
}

Answer 1

UIButton 的指定初始值设定项是 +buttonWithType:。您应该使用预定义样式之一创建按钮，或使用UIButtonTypeCustom。

UIButton *doneButton = [UIButton buttonWithType:UIButtonTypeRoundRect];
doneButton.frame = CGRectMake(260, 7.0f, 50.0f, 30.0f);
[doneButton addTarget:self action:@selector(makeDone:) forControlEvents:UIControlEventValueChanged];
[actionSheet addSubview:doneButton];