How do I make a UITableViewCell appear disabled?

A Swift extension that works well in the context I'm using it; your mileage may vary.

Swift 2.x

extension UITableViewCell {
    func enable(on: Bool) {
        for view in contentView.subviews as! [UIView] {
            view.userInteractionEnabled = on
            view.alpha = on ? 1 : 0.5
        }
    }
}

Swift 3:

extension UITableViewCell {
    func enable(on: Bool) {
        for view in contentView.subviews {
            view.isUserInteractionEnabled = on
            view.alpha = on ? 1 : 0.5
        }
    }
}

Now it's just a matter of calling myCell.enable(truthValue).

You can just disable the cell's text fields to gray them out:

Swift 4.x

cell!.isUserInteractionEnabled = false
cell!.textLabel!.isEnabled = false
cell!.detailTextLabel!.isEnabled = false

Thanks to @Ajay Sharma, I figured out how to make a UITableViewCell appear disabled:

// Mac's native DigitalColor Meter reads exactly {R:143, G:143, B:143}.
cell.textLabel.alpha = 0.439216f; // (1 - alpha) * 255 = 143
aSwitch.enabled = NO; // or [(UISwitch *)cell.accessoryView setEnabled:NO];

And then, to actually disable the cell:

cell.userInteractionEnabled = NO;