将按钮（UIButton）添加到使用drawRect绘制的自定义tableview单元格：

Question

I am currently working a on project where I have lots of custom table view cells. Part of the requirements is that the cells be able to expand if their default size can not hold all of the content. If they need to be able to expand I have to add a UIButton to the cell and when it is tapped redraw it in a bigger view where all the data fits. Currently in draw rect I essentially do this:

if([self needsExpansion]) {
    [self addExpansionButton];
}

-(void)addExpansionButton {

    self.accessoryButton = [UIButton buttonWithType:UIButtonTypeCustom];
[self.accessoryButton setShowsTouchWhenHighlighted:YES];
UIImage *buttonImage = [UIImage imageNamed:@"blue_arrow_collaps_icon.png"];
[self.accessoryButton setFrame:CGRectMake(280, 82, buttonImage.size.width, buttonImage.size.height)];
[self.accessoryButton setImage:buttonImage forState:UIControlStateNormal];
[self.accessoryButton addTarget:self action:@selector(toggleExpanded) forControlEvents:UIControlEventTouchUpInside];    
[self addSubview:self.accessoryButton];
}

This works fine, except for when I click anywhere else in the cell the button flickers and disappears. Anyone know how to propertly do this?

Answer 1

From the UITableViewCell Class Reference :

You have two ways of extending the standard UITableViewCell object beyond the given styles. To create cells with multiple, variously formatted and sized strings and images for content, you can get the cell's content view (through its contentView property) and add subviews to it.

Instead of adding the accessory button as a subview of the UITableViewCell, you should add it as a subview of the contentView:

[[self contentView] addSubview:self.accessoryButton];

Have you worked out the following problem in your design approach?: Let's say one of your cells (let's call it A) determines it needs expansion, so you add a button to it. What happens when the user scrolls through the UITableView? For performance reasons, your UITableView delegate should be using dequeueReusableCellWithIdentifier in tableView:cellForRowAtIndexPath:. So you'll be reusing A to display a different row of the table. Do you really want A to have an accessory button? Probably not, since it's now representing a different object.

You're probably better off doing the cell customization at the UITextViewDelegate. In tableView:cellForRowAtIndexPath:, you can determine if the object being displayed at the row specified needs a button, and if it does add it as a subview to the contentView.

Then again, if your table size is always relatively small (say < 50), you can use this approach Jeremy Hunt Schoenherr suggests.