如何检查inf？ Swift xcode7

Question

如果计算结果不是无限的，我如何检查Swift？

下面我的代码在打印后崩溃了“dividepointsbyrest is inf“。”如果dividepointsbyrest！= nil“检查nil。'如果dividepointsbyrest！= inf'不起作用。

var dividepointsbyrest = (BPMpoints / restDouble)
    print("dividepointsbyrest is") 
    print(dividepointsbyrest) 

    var BPMpercentD = 100.0 * dividepointsbyrest

Answer 1

Double具有isInfinite / isFinite属性。

if dividepointsbyrest.isInfinite {
    print("dividepointsbyrest is infinite")
}

或

if dividepointsbyrest.isFinite {
    print("dividepointsbyrest is finite")
}