ios – 有没有办法在Swift中对常量进行条件赋值？

我想创建一个根据条件分配不同值的不可变值.在 Scala我可以写下列内容：

let attribs = if #available(iOS 8.2,*) {
        [ NSFontAttributename: UIFont.systemFontOfSize(30,weight: UIFontWeightLight) ]
    } else {
        [ NSFontAttributename: UIFont.systemFontOfSize(30) ]
    }

但是由于Swift if语句不返回执行代码块的结果不起作用.

如果测试是针对正常的Bool,我可以使用三元条件运算符

let attribs = #available(iOS 8.2,*) ?
        [ NSFontAttributename: UIFont.systemFontOfSize(30,weight: UIFontWeightLight) ]
    :
        [ NSFontAttributename: UIFont.systemFontOfSize(30) ]

但是这不适用于iOS版本测试,我收到以下错误：

#available may only be used as condition of an 'if','guard' or 'while' statement.

我觉得我被卡住了一个var,但是除非我也可以选择我在多数情况下最终得到一个双重任务,这似乎是如此丑陋和不必要？

var attribs = [ NSFontAttributename: UIFont.systemFontOfSize(30) ]
    if #available(iOS 8.2,weight: UIFontWeightLight) ]
    }

感谢任何帮助！

let attribs: [String: Any]
if #available(iOS 8.2,*) {
    attribs = [NSFontAttributename: UIFont.systemFontOfSize(30,weight: UIFontWeightLight)]
} else {
    attribs = [NSFontAttributename: UIFont.systemFontOfSize(30)]
}