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这是 APICallsViewController 文件中的代码和几个屏幕截图。我的应用程序崩溃了，我不确定这是否是原因。

谢谢你的帮助

在此处输入图像描述

 // Customize the appearance of table view cells.
- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath {
    UILabel *textLabel;
    UILabel *detailTextLabel;
    UIButton *button;

    UIFont *cellFont = [UIFont boldSystemFontOfSize:14.0];
    UIFont *detailCellFont = [UIFont fontWithName:@"Helvetica" size:12.0];

    static NSString *CellIdentifier = @"Cell";
    UITableViewCell *cell = [tableView dequeueReusableCellWithIdentifier:CellIdentifier];
    if (cell == nil) {
        cell = [[[UITableViewCell alloc] initWithStyle:UITableViewCellStyleDefault reuseIdentifier:CellIdentifier] autorelease];
        cell.selectionStyle = UITableViewCellSelectionStyleNone;

        // Initialize API title UILabel
        textLabel = [[[UILabel alloc] initWithFrame:CGRectZero] autorelease];
        textLabel.autoresizingMask = UIViewAutoresizingFlexibleWidth | UIViewAutoresizingFlexibleRightMargin;
        textLabel.tag = TITLE_TAG;
        textLabel.font = cellFont;
        [cell.contentView addSubview:textLabel];

        // Initialize API description UILabel
        detailTextLabel = [[[UILabel alloc] initWithFrame:CGRectZero] autorelease];
        detailTextLabel.autoresizingMask = UIViewAutoresizingFlexibleWidth | UIViewAutoresizingFlexibleRightMargin;
        detailTextLabel.tag = DESCRIPTION_TAG;
        detailTextLabel.font = detailCellFont;
        detailTextLabel.textColor = [UIColor darkGrayColor];
        detailTextLabel.lineBreakMode = UILineBreakModeWordWrap;
        detailTextLabel.numberOfLines = 0;
        [cell.contentView addSubview:detailTextLabel];

        // Initialize API button UIButton
        button = [UIButton buttonWithType:UIButtonTypeRoundedRect];
        button.autoresizingMask = UIViewAutoresizingFlexibleWidth | UIViewAutoresizingFlexibleRightMargin;
        [button setBackgroundImage:[[UIImage imageNamed:@"MenuButton.png"]
                                    stretchableImageWithLeftCapWidth:9 topCapHeight:9]
                          forState:UIControlStateNormal];
        [button setTitleColor:[UIColor blackColor] forState:UIControlStateNormal];
        [button addTarget:self action:@selector(apiButtonClicked:) forControlEvents:UIControlEventTouchUpInside];
        [cell.contentView addSubview:button];
    } else {
        textLabel = (UILabel *)[cell.contentView viewWithTag:TITLE_TAG];
        detailTextLabel = (UILabel *)[cell.contentView viewWithTag:DESCRIPTION_TAG];
        // For the button cannot search by tag since it is not constant
        // and is dynamically used figure out which button is clicked.
        // So instead we loop through subviews of the cell to find the button.
        for (UIView *subview in cell.contentView.subviews) {
            if([subview isKindOfClass:[UIButton class]]) {
                button = (UIButton *)subview;
            }
        }
    }

    CGSize constraintSize = CGSizeMake(280.0f, MAXFLOAT);

    // The API title
    NSString *cellText = [[apiMenuItems objectAtIndex:indexPath.row] objectForKey:@"title"];
    CGSize labelSize = [cellText sizeWithFont:cellFont
                            constrainedToSize:constraintSize
                                lineBreakMode:UILineBreakModeWordWrap];
    textLabel.frame = CGRectMake(20, 2,
                                  (cell.contentView.frame.size.width-40),
                                  labelSize.height);
    textLabel.text = cellText;

    // The API description
    NSString *detailCellText = [[apiMenuItems objectAtIndex:indexPath.row] objectForKey:@"description"];
    CGSize detailLabelSize = [detailCellText sizeWithFont:detailCellFont
                                        constrainedToSize:constraintSize
                                            lineBreakMode:UILineBreakModeWordWrap];
    detailTextLabel.frame = CGRectMake(20, (labelSize.height + 4),
                                       (cell.contentView.frame.size.width-40),
                                       detailLabelSize.height);
    detailTextLabel.text = detailCellText;


    // The API button
    CGFloat yButtonOffset = labelSize.height + detailLabelSize.height + 15;
    button.frame = CGRectMake(20, yButtonOffset, (cell.contentView.frame.size.width-40), 44);
    [button setTitle:[[apiMenuItems objectAtIndex:indexPath.row] objectForKey:@"button"]
            forState:UIControlStateNormal];
    // Set the tag that will later identify the button that is clicked.
    button.tag = indexPath.row;


    return cell;
}
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2 回答 2

3

该button变量是一个局部变量。除非您使用 ARC，否则不能保证将其初始化为任何内容。这可能是胡说八道。分析器警告您，在您尝试向其发送消息时，它是否已分配有意义的地址尚不清楚（frame属性的设置器是您发送的消息）。

考虑一下：cellis not nil，并且您在其子视图中找不到按钮。如果是这种情况，应用程序将在没有分配给button变量的情况下到达有问题的行。它可以包含一个指向绝对任何地方的指针。如果您尝试取消引用指针以向对象发送消息，您可能会在应用程序中的任何地方乱写内存。

现在，您可能知道可以保证找到一个按钮的子类。但分析仪无法弄清楚。所以无论如何它都会警告你。

button您应该将变量初始化为nil. 如果有可能找不到按钮，您应该处理这种情况。

于 2012-05-16T18:23:28.227 回答
1

在else语句UIButton *button中未初始化。看看 if 语句中的情况：

button = [UIButton buttonWithType:UIButtonTypeRoundedRect];

但在else初始化时缺失。你可以放在后面：

} else {
        textLabel = (UILabel *)[cell.contentView viewWithTag:TITLE_TAG];
        detailTextLabel = (UILabel *)[cell.contentView viewWithTag:DESCRIPTION_TAG];
        button = (UIButton *)[cell.contentView viewWithTag:indexPath.row]; // <---- add this

并移动这个：

button.tag = indexPath.row;

前

[cell.contentView addSubview:button];

在 if 语句的末尾...

于 2012-05-16T18:27:22.830 回答