闭包

override func viewDidLoad() {
    super.viewDidLoad()
   
    
    let city = ["zhengzhou","xiamen","hefei","nanchang"]

    
    
    let cityR2 = city.sorted(by: daoxu)
    print(cityR2)
    
    
    
    
    let cityR3 = city.sorted { (a, b) -> Bool in
        return a > b
    }
    print(cityR3)
    
    
    
    
    
    let cityR4 = city.sorted { (a, b) in
        a < b
    }
    print(cityR4)
    
    
    
    
    
    let cityR5 = city.sorted {
        $0 > $1
    }
    print(cityR5)
    
    
    
    
    

}


func daoxu(a:String,b:String) -> Bool {
    return a > b
}