objective-c - Xcode 使 View 在单击时出现过渡

Question

如果这看起来像是一个基本问题，我很抱歉，但我的谷歌搜索技能似乎无法找到我的答案，我希望你能帮忙!

基本上，我希望我的应用程序有一个按钮或一个标签，然后单击它会在其下方显示一些文本(以常见问题解答的形式，如此处的链接:http://aptow.com/faq)并用它向下推所有内容.我知道如何单击并显示以前隐藏的元素，但我不确定如何实现向下滑动效果，同时在单击时将其他所有内容进一步推到屏幕下方，然后重新 -一旦用户再次单击以重新隐藏之前隐藏的内容，将其安排在屏幕顶部附近。我提供的链接准确地显示了我想要做什么。

有什么想法吗？提前致谢。

Answer 1

如果您想执行类似于您发布链接的常见问题解答页面的操作，您可以使用使用动态单元格高度的 UITableView。

一个简单的 UITableViewController 看起来像这样:

#import "ViewController.h"

@interface ViewController () {
    NSArray *data;
    int selected;
}
@end

@implementation ViewController

- (void)viewDidLoad
{
    [super viewDidLoad];
    // Do any additional setup after loading the view, typically from a nib.
    selected = -1;

    data = [NSArray arrayWithObjects:
                     [NSDictionary dictionaryWithObjectsAndKeys:@"Title 1", @"title", @"Lorem ipsum dolor bla blab bla", @"details", nil],
                      [NSDictionary dictionaryWithObjectsAndKeys:@"Title 2", @"title", @"Lorem ipsum dolor bla blab bla", @"details", nil],
                      [NSDictionary dictionaryWithObjectsAndKeys:@"Title 3", @"title", @"Lorem ipsum dolor bla blab bla", @"details", nil],
                      [NSDictionary dictionaryWithObjectsAndKeys:@"Title 4", @"title", @"Lorem ipsum dolor bla blab bla", @"details", nil],
                      [NSDictionary dictionaryWithObjectsAndKeys:@"Title 5", @"title", @"Lorem ipsum dolor bla blab bla", @"details", nil],
                      [NSDictionary dictionaryWithObjectsAndKeys:@"Title 6", @"title", @"Lorem ipsum dolor bla blab bla", @"details", nil],
                      [NSDictionary dictionaryWithObjectsAndKeys:@"Title 7", @"title", @"Lorem ipsum dolor bla blab bla", @"details", nil],nil ];

}


- (CGFloat)tableView:(UITableView *)tableView heightForRowAtIndexPath:(NSIndexPath *)indexPath {
    if (indexPath.row == selected) {
        return 130;
    } else
        return tableView.rowHeight;
}

- (NSInteger)tableView:(UITableView *)tableView numberOfRowsInSection:(NSInteger)section {
    return [data count];
}

- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath {
    static NSString *cellIdentifier = @"ci";
    UITableViewCell *cell = [tableView dequeueReusableCellWithIdentifier:cellIdentifier];
    if (!cell) {
        cell = [[UITableViewCell alloc] initWithStyle:UITableViewCellStyleDefault reuseIdentifier:cellIdentifier];
    }
    NSDictionary *tmp = [data objectAtIndex:indexPath.row];

    cell.textLabel.text = nil;


    static int TITLE_LABEL_TAG  = 122;
    UILabel *titleLabel = (UILabel *)[cell.contentView viewWithTag:TITLE_LABEL_TAG];
    if (!titleLabel) {
        titleLabel = [[UILabel alloc] initWithFrame:CGRectNull];
        titleLabel.tag = TITLE_LABEL_TAG;
        [cell.contentView addSubview:titleLabel];
        titleLabel.backgroundColor = [UIColor clearColor];
        titleLabel.numberOfLines = 1;
        titleLabel.font = [UIFont boldSystemFontOfSize:16];
        [cell.contentView addSubview:titleLabel];
    }
    titleLabel.frame = (CGRectMake(8, 8, cell.contentView.frame.size.width-16, 20));
    titleLabel.text = [tmp objectForKey:@"title"];

    static int DETAIL_LABEL_TAG  = 123;
    UILabel *detailLabel = (UILabel *)[cell.contentView viewWithTag:DETAIL_LABEL_TAG];
    if (!detailLabel) {
        detailLabel = [[UILabel alloc] initWithFrame:CGRectNull];
        detailLabel.tag = DETAIL_LABEL_TAG;
        [cell.contentView addSubview:detailLabel];
        detailLabel.backgroundColor = [UIColor clearColor];
        detailLabel.numberOfLines = 0;
    }
    if (indexPath.row == selected) {
        detailLabel.frame = (CGRectMake(8, 30, cell.contentView.frame.size.width-16, 100));

        detailLabel.hidden = NO;
        detailLabel.text = [tmp objectForKey:@"details"];
    } else {
        detailLabel.hidden = YES;
    }

    return cell;
}

- (void)tableView:(UITableView *)tableView didSelectRowAtIndexPath:(NSIndexPath *)indexPath {

    NSMutableArray *ip2reload = [NSMutableArray array];
    if (selected > -1 && selected != indexPath.row)
        [ip2reload addObject:[NSIndexPath indexPathForRow:selected inSection:0]];
    [ip2reload addObject:[NSIndexPath indexPathForRow:indexPath.row inSection:0]];
    selected = indexPath.row;
    [tableView reloadRowsAtIndexPaths:ip2reload withRowAnimation:UITableViewRowAnimationAutomatic];
}


@end

您肯定需要根据内容计算所选行的实际行高(例如，如此处所述:Iphone - when to calculate heightForRowAtIndexPath for a tableview when each cell height is dynamic?)。

并且您可以使用 scrollToRowAtIndexPath:atScrollPosition:animated 来确保所选单元格位于屏幕顶部。