IOS --- Summary of common global functions and extension in Swift (continuous update)

IOS --- Summary of common global functions and extension in Swift (continuous update)

Sort out the common Swift global functions and extension (because macro definitions cannot be used in Swift) in iOS development as follows.
For a summary of Objective-C's macro definition, refer to the frequently-used macro definition in Objective-C in the blog iOS-Summary (continuously updated ).

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