How can I get indexPath.row in cell.swift

Easy.. You can do like this inside button action:

let section = 0
let row = sender.tag
let indexPath = IndexPath(row: row, section: section)
let cell: myTableCell = self.feedTableView.cellForRow(at: indexPath) as! myTableCell

And afterwards in cellForRowAtIndexPath:

// add the row as the tag
cell.button.tag = indexPath.row

I have created a UIResponder extension with a recursive method that you can use in any UIView (which inherits from UIResponder) to find a parent view of a specific type.

import UIKit

extension UIResponder {
    /**
     * Returns the next responder in the responder chain cast to the given type, or
     * if nil, recurses the chain until the next responder is nil or castable.
     */
    func next<U: UIResponder>(of type: U.Type = U.self) -> U? {
        return self.next.flatMap({ $0 as? U ?? $0.next() })
    }
}

Using this, we can extend UITableViewCell with some convenient read-only computed properties for the table view and index path of the cell.

extension UITableViewCell {
    var tableView: UITableView? {
        return self.next(of: UITableView.self)
    }

    var indexPath: IndexPath? {
        return self.tableView?.indexPath(for: self)
    }
}

Here is how you could use it in your example:

@IBAction func likeBtnTapped(_ sender: AnyObject) {
    //declare title of button
    let title = sender.title(for: UIControlState())

    //I want get indexPath.row in here!
    self.indexPath.flatMap { print($0) }
}

Swift 4+

Try this inside your cell.

func getIndexPath() -> IndexPath? {
    guard let superView = self.superview as? UITableView else {
        print("superview is not a UITableView - getIndexPath")
        return nil
    }
    indexPath = superView.indexPath(for: self)
    return indexPath
}