將iOS開發中常用的Swift全局函數和extension（因Swift中不能使用宏定義）整理如下。
而對於Objective-C，其宏定義總結請參考博客iOS — 總結Objective-C中常用的宏定義（持續更新中）。

//
//  Global.swift
//
//  useful global methods and extension for Chris Hu
//

import Foundation

func isIPhone4() -> Bool {
    return UIScreen.mainScreen().currentMode?.size == CGSizeMake(640, 960)
}
func isIPhone5() -> Bool {
    return UIScreen.mainScreen().currentMode?.size == CGSizeMake(640, 1136)
}
func isIPhone6() -> Bool {
    return UIScreen.mainScreen().currentMode?.size == CGSizeMake(750, 1334)
}
func isIPhone6Plus() -> Bool {
    return UIScreen.mainScreen().currentMode?.size == CGSizeMake(1242, 2208)
}
func isIPhone6PlusBigMode() -> Bool {
    return UIScreen.mainScreen().currentMode?.size == CGSizeMake(1125, 2001)
}


func currentLanguage() -> String {
    return NSLocale.preferredLanguages().first!
}

func systemVersion() -> String {
    return UIDevice.currentDevice().systemVersion
}

func appVersion() -> String {
    return String(NSBundle.mainBundle().infoDictionary!["CFBundleShortVersionString"]!)
}


extension UIColor {
    public convenience init(hexString: UInt32, alpha: CGFloat = 1.0) {
        let red     = CGFloat((hexString & 0xFF0000) >> 16) / 255.0
        let green   = CGFloat((hexString & 0x00FF00) >> 8 ) / 255.0
        let blue    = CGFloat((hexString & 0x0000FF)      ) / 255.0
        self.init(red: red, green: green, blue: blue, alpha: alpha)
    }
}

extension UITableViewDataSource {
    // return total rows in the tableView
    func totalRows(tableView: UITableView) -> Int {
        let totalSections = self.numberOfSectionsInTableView!(tableView) ?? 1
        var section = 0, total = 0
        while section < totalSections {
            total += self.tableView(tableView, numberOfRowsInSection: section)
            section++
        }
        return total
    }
}