Adding UIScrollView to table cell seems to affect table scroll performance - ios

Question

I'm not sure this was poor implementation or a poor decision to start with, but I'm attempting to add a horizontal UIScrollView inside of each cell within my UITableView. I add it is as a subview to the cell's contentView, then call cell.clipsToBounds = true (FYI, I'm using RubyMotion). When I tap a button on the cell, I use beginUpdates/endUpdates to trigger heightForRowAtIndexPath to expand the cell's height and show the "hidden" scrollview.
Anyway, since doing that my table's scroll is a bit sluggish. I've added my code below and am wondering if my implementation can be improved to fix that scroll performance. Any help/insight is helpful (though if possible I'd like to try and keep the scroll views).
my_array = [
["Hi", "there", "one"],
["Hi", "there", "two"],
["Hi", "there", "three"],
["Hi", "there", "four"],
]
scroll_frame = CGRectMake(
0, rowHeight - 1, hidden_width, 51
)
hidden_scroll = UIScrollView.alloc.initWithFrame(scroll_frame)
hidden_scroll.alwaysBounceHorizontal = true
hidden_scroll.bounces = true
hidden_scroll.contentSize = CGSizeMake(hidden_width * my_array.size, scroll_frame.size.height)
hidden_scroll.delegate = parent
hidden_scroll.clipsToBounds = true
hidden_scroll.pagingEnabled = true
hidden_scroll.showsHorizontalScrollIndicator = false
hidden_scroll.layer.borderWidth = 1
hidden_scroll.layer.borderColor = UIColor.colorWithRed(200.0/255, green:200.0/255, blue:200.0/255, alpha: 1).CGColor
hidden_scroll.backgroundColor = UIColor.colorWithRed(248.0/255, green:248.0/255, blue:248.0/255, alpha: 1)
hidden_scroll.scrollEnabled = false
my_array.each_with_index do |data, index|
hidden_view = UIView.alloc.initWithFrame(CGRectMake(
(parent.view.frame.size.width * index), 0, parent.view.frame.size.width, 50
)
)
label_frame = CGRectMake(
40, 5, (parent.view.frame.size.width - 40 - 7) * 2/3, 40
)
label = UILabel.alloc.initWithFrame(label_frame)
label.font = UIFont.boldSystemFontOfSize(11)
label.backgroundColor = UIColor.clearColor
label.text = data[0]
label.numberOfLines = 0
label.lineBreakMode = UILineBreakModeWordWrap
label_size = data[0].sizeWithFont(label.font)
label.sizeToFit
new_frame = label.frame
new_frame.origin.y = (50 - label.frame.size.height) / 2
new_frame.size.height = label.frame.size.height
label.frame = new_frame
button = UIButton.buttonWithType(UIButtonTypeCustom)
button.backgroundColor = UIColor.orangeColor
button.font = UIFont.systemFontOfSize(11)
button.setTitle(data[3].upcase, forState:UIControlStateNormal)
button.setTitleColor(UIColor.whiteColor, forState:UIControlStateNormal)
button.layer.cornerRadius = 2.0
button.instance_variable_set(:#data, data)
button_size = data[3].upcase.sizeWithFont(button.font)
button.frame = [
[label.frame.origin.x + label_frame.size.width + 5, (50 - label_size.height) / 2 - 3],
[80, button_size.height + 6]
]
button.addTarget(parent, action:"add_user_goal:", forControlEvents:UIControlEventTouchUpInside)
hidden_view.addSubview(label)
hidden_view.addSubview(button)
hidden_scroll.insertSubview(hidden_view, belowSubview: cell.contentView)
end

Answer 1

Since the UIScrollView isn't in view anyway, try creating the UIScrollView only when the user taps the cell to view it. Before then, there's just an empty area of the cell.
For cleaner code, I'd also recommend subclassing UIScrollView and doing your customization in a custom initializer.
class CellScrollView < UIScrollView
def initWithCustom(args={})
self.initWithFrame(args[:frame])
# ... all your customizations. Use the args hash to pass in any other data you need.
self
end
end