xcode 我试图将 UIActivityIndicatorView 置于 UITableView 上，但它有上边距
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I am trying to center UIActivityIndicatorView over a UITableView but it has top margin
提问by Richard Knop
I am using Xcode 4.2 on Snow Leopard. What I am trying to do. Basically, I have a master view controller with a table view. In order to populate the table view I need to call an API and download the information from there.
我在雪豹上使用 Xcode 4.2。我正在尝试做的事情。基本上，我有一个带有表视图的主视图控制器。为了填充表视图，我需要调用 API 并从那里下载信息。
While downloading the data from the API, I would like to show an activity indicator in order to let a user know something is happening and the app is not stuck.
从 API 下载数据时，我想显示一个活动指示器，以便让用户知道正在发生的事情并且应用程序没有卡住。
What I have done is I have a created a new UIView over the table view with alpha 0.5 and put an activity indicator in its middle. This is the code I execute when the master controller view loads:
我所做的是我在 alpha 0.5 的表视图上创建了一个新的 UIView，并在其中间放置了一个活动指示器。这是我在主控制器视图加载时执行的代码：
// Show the activity indicator
self.overlayView = [[UIView alloc] init];
self.overlayView.backgroundColor = [UIColor colorWithRed:0 green:0 blue:0 alpha:0.5];
self.overlayView.frame = self.tableView.frame;
self.activityIndicator = [[UIActivityIndicatorView alloc] initWithActivityIndicatorStyle:UIActivityIndicatorViewStyleWhiteLarge];
CGRect frame = self.overlayView.frame;
self.activityIndicator.center = CGPointMake(frame.size.width/2, frame.size.height/2);
[self.overlayView addSubview:self.activityIndicator];
[self.activityIndicator startAnimating];
[self.tableView addSubview:self.overlayView];
When the data is loaded from the API, I hide the overlay view and the activity indicator:
当从 API 加载数据时，我隐藏了叠加视图和活动指示器：
[self.activityIndicator removeFromSuperview];
[self.overlayView removeFromSuperview];
It is working fine but the problem is the overlay view is not aligned properly, it has a top margin and it is not looking good. Here's how it looks:
它工作正常，但问题是叠加视图没有正确对齐，它有一个上边距并且看起来不太好。这是它的外观：
回答by Paul.s
Dont't use
不要使用
self.overlayView.frame = self.tableView.frame;
instead use
而是使用
self.overlayView.frame = self.tableView.bounds;
It looks like your tableView has origin.y = 20.0f;
看起来你的 tableView 有 origin.y = 20.0f;
Other notes
其他注意事项
The designated initializer for UIViewis
initWithFrame:so you should be using that.You can simply this
self.activityIndicator.center = CGPointMake(frame.size.width/2, frame.size.height/2);to
self.activityIndicator.center = self.overlayView.center;
UIView的指定初始值设定项是
initWithFrame:您应该使用的。你可以简单地这个
self.activityIndicator.center = CGPointMake(frame.size.width/2, frame.size.height/2);到
self.activityIndicator.center = self.overlayView.center;
