关于Swift 字典 Dictionary

// 字典
var users = [1:"jiang", 2:"jzh", 3:"hao"]

for (key, value) in users
{
    print("\(key):\(value)")
}

for key in users.keys
{
    print(key)
}

for values in users.values
{
    print(values)
}

users.updateValue("haohao", forKey:3)
print(users[3] ?? "")