Swift實現頁面元素的絕對位置（水平置中，垂直置中，右上方等等）

1，各種常見位置的定位

使用按鈕示範如何將元件置中（水平置中、垂直置中），以及放置在邊角處（左上方，右上方，左下角，右下角）

代碼如下

複製代碼

import UIKit   class ViewController: UIViewController {       override func viewDidLoad() {         super.viewDidLoad()           let btn1 = createButton("左上")         self.view.addSubview(btn1)                   let btn2 = createButton("右上")         btn2.frame.origin.x = self.view.bounds.width - btn2.frame.width         self.view.addSubview(btn2)                   let btn3 = createButton("左下")         btn3.frame.origin.y = self.view.bounds.height - btn3.frame.height         self.view.addSubview(btn3)                   let btn4 = createButton("右下")         btn4.frame.origin = CGPoint(x: self.view.bounds.width - btn4.frame.width,             y: self.view.bounds.height - btn4.frame.height)         self.view.addSubview(btn4)                   let btn5 = createButton("置中")         btn5.center = CGPoint(x: self.view.bounds.width / 2,             y: self.view.bounds.height / 2)         self.view.addSubview(btn5)                   let btn6 = createButton("上中")         btn6.center.x = self.view.bounds.width / 2         self.view.addSubview(btn6)                   let btn7 = createButton("左中")         btn7.center.y = self.view.bounds.height / 2         self.view.addSubview(btn7)                   let btn8 = createButton("右中")         btn8.frame.origin.x = self.view.bounds.width - btn8.frame.width         btn8.center.y = self.view.bounds.height / 2         self.view.addSubview(btn8)                   let btn9 = createButton("下中")         btn9.center.x = self.view.bounds.width / 2         btn9.frame.origin.y = self.view.bounds.height - btn9.frame.height         self.view.addSubview(btn9)     }           func createButton(title: String) -> UIButton {         //建立一個ContactAdd類型的按鈕         let button:UIButton = UIButton(type:.Custom)         //設定按鈕大小         //button.frame=CGRectMake(0, 0, 80, 50)         button.frame.size = CGSize(width: 80, height: 50)         //設定按鈕文字         button.setTitle(title, forState:UIControlState.Normal)         button.backgroundColor=UIColor.orangeColor()         return button     }       override func didReceiveMemoryWarning() {         super.didReceiveMemoryWarning()     } }

2，定位從狀態列（statusBar）下方開始

有時我們放置的頁面元素不想與狀態列重合，而是從狀態列下方開始，那麼加上狀態列高度即可。

 

代碼如下

複製代碼

let statusFrame = UIApplication.sharedApplication().statusBarFrame   let btn1 = createButton("左上") btn1.frame.origin.y = statusFrame.height self.view.addSubview(btn1)   let btn2 = createButton("右上") btn2.frame.origin.x = self.view.bounds.width - btn2.frame.width btn2.frame.origin.y = statusFrame.height self.view.addSubview(btn2)   let btn6 = createButton("上中") btn6.center.x = self.view.bounds.width / 2 btn6.frame.origin.y = statusFrame.height self.view.addSubview(btn6)

3，定位從導覽列（navigationBar）下方開始

同樣的，如果頁面上有導覽列，而元素又不想被導覽列遮住。那麼將其加上導覽列的座標和高度即可。

 

代碼如下

複製代碼

import UIKit   class ViewController: UIViewController {       override func viewDidLoad() {         super.viewDidLoad()           var marginTop:CGFloat = 0         if let rect = self.navigationController?.navigationBar.frame {             marginTop = rect.height + rect.origin.y         }                   let btn1 = createButton("左上")         btn1.frame.origin.y = marginTop         self.view.addSubview(btn1)                   let btn2 = createButton("右上")         btn2.frame.origin.x = self.view.bounds.width - btn2.frame.width         btn2.frame.origin.y = marginTop         self.view.addSubview(btn2)                   let btn6 = createButton("上中")         btn6.center.x = self.view.bounds.width / 2         btn6.frame.origin.y = marginTop         self.view.addSubview(btn6)                   let btn3 = createButton("左下")         btn3.frame.origin.y = self.view.bounds.height - btn3.frame.height         self.view.addSubview(btn3)                   let btn4 = createButton("右下")         btn4.frame.origin = CGPoint(x: self.view.bounds.width - btn4.frame.width,             y: self.view.bounds.height - btn4.frame.height)         self.view.addSubview(btn4)                   let btn5 = createButton("置中")         btn5.center = CGPoint(x: self.view.bounds.width / 2,             y: (self.view.bounds.height + marginTop) / 2)         self.view.addSubview(btn5)                   let btn7 = createButton("左中")         btn7.center.y = (self.view.bounds.height + marginTop) / 2         self.view.addSubview(btn7)                   let btn8 = createButton("右中")         btn8.frame.origin.x = self.view.bounds.width - btn8.frame.width         btn8.center.y = (self.view.bounds.height + marginTop) / 2         self.view.addSubview(btn8)                   let btn9 = createButton("下中")         btn9.center.x = self.view.bounds.width / 2         btn9.frame.origin.y = self.view.bounds.height - btn9.frame.height         self.view.addSubview(btn9)     }           func createButton(title: String) -> UIButton {         //建立一個ContactAdd類型的按鈕         let button:UIButton = UIButton(type:.Custom)         //設定按鈕大小         //button.frame=CGRectMake(0, 0, 80, 50)         button.frame.size = CGSize(width: 80, height: 50)         //設定按鈕文字         button.setTitle(title, forState:UIControlState.Normal)         button.backgroundColor=UIColor.orangeColor()         return button     }       override func didReceiveMemoryWarning() {         super.didReceiveMemoryWarning()     } }