Clarence Clarence - 1 month ago 4
Swift Question

Fade in UITableViewCell row by row in Swift

I am new to swift, I am trying to have a UITableView and the cells will be animated to appear one by one. How can I do that? Also, if the newly appeared row of cell not on the screen (hiding below the table). How can I move the table up when each cell appear?

var tableData1: [String] = ["1", "2", "3", "4", "5", "6", "7"]

override func viewWillAppear(animated: Bool) {
tableView.scrollEnabled=false
tableView.alpha=0.0
NSTimer.scheduledTimerWithTimeInterval(NSTimeInterval(3), target: self, selector: "animateTable", userInfo: nil, repeats: false)
}

func tableView(tableView: UITableView, numberOfRowsInSection section: Int) -> Int {
return self.tableData1.count
}

func tableView(tableView: UITableView, cellForRowAtIndexPath indexPath: NSIndexPath) -> UITableViewCell {

let cell:TblCell = self.tableView.dequeueReusableCellWithIdentifier("cell") as! TblCell
cell.lblCarName.textAlignment = NSTextAlignment.Justified;
return cell
}

func animateTable() {

//what should be the code?//
}

Answer

In the UITableView, the rows are prepared automatically for you when they get to be in your "range vision". I'm assuming you are, at least not initially, being able to scroll the tableView, so we would scroll it programmatically making the rows appear as it goes. How are we doing that? Actually UITableView has a method that let us scroll it to a specific row:

scrollToRowAtIndexPath(indexPath : NSIndexPath, atScrollPosition : UITableViewScrollPosition, animated : Bool);

I'm too tired to write the code, so I'm going to try to explain. First, for every cell you set alpha to 0, as soon as they get loaded (cellForRowAtIndexPath). Then let's suppose our screen fits the 5 first rows. You are going to animate their alphas sequentially (using UIView.animateWithDuration ) until the fifth one (index 4), then you are going to scrollToRowAtIndexPath passing NSIndexPath using 5, then 6,... until the rest of them (using scrollPosition = .Bottom). And for each of them, you would animate as soon as they get loaded. Just remember to put some time between this interactions. (animate first, run NSTimer to the second, and it goes on). And the boolean animated should be true of course.

Comments