UIButton不能以UITableViewCell中的所有設備爲中心 - Swift

Question

我創建了一個自定義的UITableViewCell，它以編程方式添加到我的視圖控制器中。自定義單元格包含一個按鈕。問題是我無法實現在所有設備上居中對齊的按鈕。如果它是5s模擬器，並且我使用self.frame.width作爲按鈕框架的x座標，那麼它將居中 - 但不在6或6s上，但是如果我使用super.frame.width作爲x-coord ，然後以6模擬器爲中心。有誰知道我可以如何讓它集中在所有設備屏幕上？這裏是我的自定義按鈕的代碼，我簡單地返回它作爲一個UITableViewCell中的tableView委託在我的ViewController ...

import Foundation 
import UIKit 

public class ButtonCell: UITableViewCell { 

    //Custom button to be added to the last cell to submit 
    let buttonImage = UIImage(named: "add_pub_button") as UIImage? 
    let button = UIButton(type: UIButtonType.Custom) as UIButton 

    /** 
    Creates the ButtonCell 

    - parameter style:   A constant indicating a cell style. See UITableViewCellStyle for descriptions of these constants. 
    - parameter reuseIdentifier: A string used to identify the cell object if it is to be reused for drawing multiple rows of a table view. Pass nil if the cell object is not to be reused. You should use the same reuse identifier for all cells of the same form. 

    - returns: An initialized TextInputCell object or nil if the object could not be created. 
    */ 
    override public init(style: UITableViewCellStyle, reuseIdentifier: String?) { 
     super.init(style: style, reuseIdentifier: reuseIdentifier) 
     setup() 
    } 

    private func setup() { 

     //Overhangs the view slightly to avoid invalid constraints. 
     self.clipsToBounds = true 
     self.backgroundView = nil 
     self.backgroundColor = nil 
     self.tintColor = nil 
     self.selectionStyle = .None 

     button.frame = CGRectMake((self.frame.width - 134)/2, 0, 134, 44) 
     button.tintColor = nil 
     button.backgroundColor = nil 
     button.setImage(buttonImage, forState: .Normal) 

     self.contentView.addSubview(button) 
    } 

    /** 
    Needed for initialization from a storyboard. 
    - parameter aDecoder: An unarchiver object. 
    - returns: An initialized ButtonCell object or nil if the object could not be created. 
    */ 
    required public init?(coder aDecoder: NSCoder) { 
     super.init(coder: aDecoder) 
     setup() 
    } 
} 

Answer 1

剛剛設置的框架相關的操作layoutSubviews方法

例如，

private func setup() { 

    //Overhangs the view slightly to avoid invalid constraints. 
    self.clipsToBounds = true 
    self.backgroundView = nil 
    self.backgroundColor = nil 
    self.tintColor = nil 
    self.selectionStyle = .None 

    //no need of setting the frame of button hear 
    //at the time initialisation there is no frame available for cell 
    //button.frame = CGRectMake((self.frame.width - 134)/2, 0, 134, 44) 
    button.tintColor = nil 
    button.backgroundColor = nil 
    button.setImage(buttonImage, forState: .Normal) 

    self.contentView.addSubview(button) 
} 

//set it hear because frame of the cell available hear 
override func layoutSubviews() { 
    super.layoutSubviews() 
    button.frame = CGRectMake((self.frame.width - 134)/2, 0, 134, 44) 
} 

Answer 2

我不會用框架。我會用constraints。您可以輕鬆地創建水平通過中心這個約束如下：

button.translatesAutoresizingMaskIntoConstraints = false 
let centerX = NSLayoutConstraint(item: button, attribute: .CenterX, relatedBy: .Equal, toItem: self, attribute: .CenterX, multiplier: 1, constant: 0) 
self.addConstraint(centerX)