How do I add an extra separator to the top of a UITableView?

问题:

I have a view for the iPhone that is basically split in two, with an informational display in the top half, and a UITableView for selecting actions in the bottom half. The problem is that there is no border or separator above the first cell in the UITableView, so the first item in the list looks funny. How can I add an extra separator at the top of the table, to separate it from the display area above it?

Here's the code to build the cells - it's pretty straightforward. The overall layout is handled in a xib.

- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath {     static NSString *CellIdentifier = @"Cell";      UITableViewCell *cell = [tableView dequeueReusableCellWithIdentifier:CellIdentifier];     if (cell == nil) {         cell = [[[UITableViewCell alloc] initWithStyle:UITableViewCellStyleDefault reuseIdentifier:CellIdentifier] autorelease];         cell.accessoryType = UITableViewCellAccessoryDisclosureIndicator;     }      switch(indexPath.row) {         case 0: {             cell.textLabel.text = @"Action 1";             break;         }         case 1: {             cell.textLabel.text = @"Action 2";             break;         }         // etc.......     }     return cell; }

回答1:

To replicate the standard iOS separator lines, I use a 1 px (not 1 pt) hair line tableHeaderView with the table view's separatorColor:

// in -viewDidLoad self.tableView.tableHeaderView = ({UIView *line = [[UIView alloc] initWithFrame:CGRectMake(0, 0, self.tableView.frame.size.width, 1 / UIScreen.mainScreen.scale)];     line.backgroundColor = self.tableView.separatorColor;     line; });

The same in Swift (thanks, Dane Jordan, Yuichi Kato, Tony Merritt):

let px = 1 / UIScreen.main.scale let frame = CGRect(x: 0, y: 0, width: self.tableView.frame.size.width, height: px) let line = UIView(frame: frame) self.tableView.tableHeaderView = line line.backgroundColor = self.tableView.separatorColor

回答2:

I just got hit with this same problem and realised that the separator at the top is only displayed whilst scrolling the table.

What I then did was the following

1. In Interface Builder go to "Scroll View Size"
2. Set the Content Insets of Top to 1

Alternatively in code you could do

[tableView setContentInset:UIEdgeInsetsMake(1.0, 0.0, 0.0, 0.0)];

NOTE: This no longer works for iOS7 as the separators are no longer shown at all.

回答3:

I had the same problem and could not find an answer. So I added a line to the bottom of my table header.

CGRect  tableFrame = [[self view] bounds] ;  CGFloat headerHeight = 100;         UIView * headerView = [[UIView alloc] initWithFrame:CGRectMake(0,0,tableFrame.size.width, headerHeight)]; // Add stuff to my table header...  // Create separator UIView *lineView = [[UIView alloc] initWithFrame:CGRectMake(0, headerHeight-1, tableFrame.size.width, 1)] ; lineView.backgroundColor = [UIColor colorWithRed:224/255.0 green:224/255.0 blue:224/255.0 alpha:1.0]; [headerView addSubview:lineView];  self.tableView.tableHeaderView = headerView;

回答4:

In complement of Ortwin's answer, if you need to add some margin to your top separator to fit the separator inset, you have to embedded your top separator in another view :

UIView *headerView = [[UIView alloc] initWithFrame:CGRectMake(0, 0, self.tableView.frame.size.width, 1 / UIScreen.mainScreen.scale)]; UIView *topSeparator = [[UIView alloc] initWithFrame:CGRectMake(self.tableView.separatorInset.left, 0, self.tableView.frame.size.width - self.tableView.separatorInset.left - self.tableView.separatorInset.right, 1 / UIScreen.mainScreen.scale)]; topSeparator.backgroundColor = self.tableView.separatorColor; [headerView addSubview:topSeparator]; self.tableView.tableHeaderView = headerView;

Hope it helps.

回答5:

I made a UITableView extension that displays a native style separator on top of the UITableView, while the table gets scrolled.

Here's the code (Swift 3)

fileprivate var _topSeparatorTag = 5432 // choose unused tag  extension UITableView {      fileprivate var _topSeparator: UIView? {         return superview?.subviews.filter { $0.tag == _topSeparatorTag }.first     }      override open var contentOffset: CGPoint {         didSet {             guard let topSeparator = _topSeparator else { return }              let shouldDisplaySeparator = contentOffset.y > 0              if shouldDisplaySeparator && topSeparator.alpha == 0 {                 UIView.animate(withDuration: 0.15, animations: {                     topSeparator.alpha = 1                 })             } else if !shouldDisplaySeparator && topSeparator.alpha == 1 {                 UIView.animate(withDuration: 0.25, animations: {                     topSeparator.alpha = 0                 })             }         }     }      // Adds a separator to the superview at the top of the table     // This needs the separator insets to be set on the tableView, not the cell itself     func showTopSeparatorWhenScrolled(_ enabled: Bool) {         if enabled {             if _topSeparator == nil {                 let topSeparator = UIView()                 topSeparator.backgroundColor = separatorColor?.withAlpha(newAlpha: 0.85) // because while scrolling, the other separators seem lighter                 topSeparator.translatesAutoresizingMaskIntoConstraints = false                  superview?.addSubview(topSeparator)                  topSeparator.leftAnchor.constraint(equalTo: self.leftAnchor, constant: separatorInset.left).isActive = true                 topSeparator.rightAnchor.constraint(equalTo: self.rightAnchor, constant: separatorInset.right).isActive = true                 topSeparator.topAnchor.constraint(equalTo: self.topAnchor).isActive = true

let onePixelInPoints = CGFloat(1) / UIScreen.main.scale topSeparator.heightAnchor.constraint(equalToConstant: onePixelInPoints).isActive = true

                topSeparator.tag = _topSeparatorTag                 topSeparator.alpha = 0                  superview?.setNeedsLayout()             }         } else {             _topSeparator?.removeFromSuperview()         }     }      func removeSeparatorsOfEmptyCells() {         tableFooterView = UIView(frame: .zero)     } }

To enable it, simply call tableView.showTopSeparatorWhenScrolled(true) after you set your delegate for your UITableView

回答6:

I solved this by adding one extra line at the beginning of the table. Just have to set its height to 1, set its the text to empty, disable user interaction for it and in the whole code adjust the indexPath.row value.

回答7:

Add a separator between header view and first row :- In view for Header in section delegate method add a subview self.separator //@property (nonatomic, strong) UIImageView *separator;

- (CGFloat)tableView:(UITableView *)tableView heightForHeaderInSection:(NSInteger)section {  return 41;  }   - (UIView *)tableView:(UITableView *)tableView viewForHeaderInSection:(NSInteger)section {  self.headerView = [[UIView alloc] init]; self.headerView.backgroundColor = [UIUtils colorForRGBColor:TIMESHEET_HEADERVIEW_COLOR];  self.separator = [[UIImageView alloc]initWithImage:[UIImage imageNamed:@"seperator.png"]]; self.separator.frame = CGRectMake(0,40,self.view.frame.size.width,1); [self.headerView addSubview:self.separator]; return self.headerView;  }

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