UITutCellView中的UIButton图像问题 [英] issue with UIButton image in UITableCellView
问题描述
我正在制作一个简单的计时器应用程序。我有一个多行的uitable。在那张桌子里，我放了一个UIButton。一切正常，到目前为止很好，即我看到按钮出现在每一行。我接下来需要做的是为UIButton设置图像，例如如果计时器正在运行，我想在UIButton中显示stop_button_image，如果计时器已启动，我想将按钮上的UIImage设置为start_button_image
I am making a simple timer app. I have a uitable with multiple rows. In that table I have put a UIButton. Everything works and so far so good i.e. I see the button appear in each row. What I needed to do next was to set an image for the UIButton e.g. if the timer was running I wanted to show stop_button_image in the UIButton and if the timer had started I wanted to set the UIImage on the button to start_button_image
问题是如果表得到刷新然后我得到一个令人讨厌的回溯取决于我放置UIButton setimage代码的位置。这是我的代码供参考。
The problem is that if the table gets refreshed then I get a nasty traceback depending upon where I had put the UIButton setimage code. Here is my code for reference.
//WORKING CODE: (NOT THAT I WANT)
- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath
{
//TESTING - Button
UIButton *button = [UIButton buttonWithType:UIButtonTypeCustom];
// Try to retrieve from the table view a now-unused cell with the given identifier.
UITableViewCell *cell = [tableView dequeueReusableCellWithIdentifier:CellIdentifier];
// If no cell is available, create a new one using the given identifier.
if (cell == nil)
{
// Use the default cell style.
cell = [[UITableViewCell alloc] initWithStyle:UITableViewCellStyleSubtitle reuseIdentifier:CellIdentifier];
//TESTING - Button
[button addTarget:self
action:@selector(timerStopStart:)
forControlEvents:UIControlEventTouchDown];
[button setTitle:@"Start/Stop" forState:UIControlStateNormal];
button.frame = CGRectMake(5.0f, 5.0f, 72.0f, 77.0f);
button.tag = indexPath.row;
[cell addSubview:button];
//THIS WORKS IF I PUT THIS HERE
[button setImage:[UIImage imageNamed:@"button_pause.png"] forState:UIControlStateNormal];
}
else
{
//NSLog(@"went here 2");
button = (UIButton *) [cell viewWithTag:indexPath.row];
}
//some other logic
}
// CODE BREAKS HERE
//CODE BREAKS HERE
- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath
{
//TESTING - Button
UIButton *button = [UIButton buttonWithType:UIButtonTypeCustom];
// Try to retrieve from the table view a now-unused cell with the given identifier.
UITableViewCell *cell = [tableView dequeueReusableCellWithIdentifier:CellIdentifier];
// If no cell is available, create a new one using the given identifier.
if (cell == nil)
{
// Use the default cell style.
cell = [[UITableViewCell alloc] initWithStyle:UITableViewCellStyleSubtitle reuseIdentifier:CellIdentifier];
//TESTING - Button
[button addTarget:self
action:@selector(timerStopStart:)
forControlEvents:UIControlEventTouchDown];
[button setTitle:@"Start/Stop" forState:UIControlStateNormal];
button.frame = CGRectMake(5.0f, 5.0f, 72.0f, 77.0f);
button.tag = indexPath.row;
[cell addSubview:button];
}
else
{
//NSLog(@"went here 2");
button = (UIButton *) [cell viewWithTag:indexPath.row];
}
//CODE BREAKS HERE
[button setImage:[UIImage imageNamed:@"button_pause.png"] forState:UIControlStateNormal];
//some other logic
}
问题是当表被刷新时，它调用代码按钮=（UIButton *）[cell viewWithTag：indexPath.row];我知道这只是一个参考。
The problem is that when the table gets refreshed it calls the section with code button = (UIButton *) [cell viewWithTag:indexPath.row]; which I know is just a reference.
这是我在iOS模拟器中遇到的错误。我真的想把那个图像代码放在cell == null check之外。有什么线索可以做到这一点？
Here is the error I get in iOS simulator. I really want to put that image code outside the cell==null check. Any clues how this can be done?
这是我在模拟器中得到的错误
Here is the error that I get in the simulator
2012-06-14 12:39:27.246 Timers[5381:10a03] -[UITableViewCell setImage:forState:]: unrecognized selector sent to instance 0x73706e0
2012-06-14 12:39:27.247 Timers[5381:10a03] *** Terminating app due to uncaught exception 'NSInvalidArgumentException', reason: '-[UITableViewCell setImage:forState:]: unrecognized selector sent to instance 0x73706e0'
*** First throw call stack:
(0x150b052 0x16bbd0a 0x150cced 0x1471f00 0x1471ce2 0x136c6 0x7b5e0f 0x7b6589 0x7a1dfd 0x7b0851 0x75b322
推荐答案
问题可能是当indexPath.row为零时。在这种情况下，你调用 viewWithTag：0 但是因为任何UIView的标记都是0默认情况下，您的单元格的子视图很可能有一个值为0的标记，而不仅仅是您的UIButton。
The problem is probably when the indexPath.row is zero. In that case, you call viewWithTag:0 but as the tag of any UIView is 0 by default, there are chances that a lot of your cell's subview have a tag with the value 0, not only your UIButton.
要避免此问题，请尝试添加在对indexPath.row执行常量（如100）之前，将其影响到标记，以便第0行的按钮将具有标记100而不是0（并且第1行的按钮将具有标记101，依此类推...... ），避免与标记为0的任何其他子视图混淆。
To avoid this issue, try adding a constant (like 100) to your indexPath.row before affecting it to the tag, so that your button at row 0 will have the tag 100 and not 0 (and button at row 1 will have the tag 101, and so on…), avoiding it to be confused with any other subview with tag 0.
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