Calendar.current.date(bySettingHour编译需要花费很长时间

问题描述：

我已使用Calendar.current.date(bySettingHour代码设置特定日期.问题是，编译大约需要4秒钟的时间

I have used Calendar.current.date(bySettingHour code for setting particular date. Problem is it takes so long to compile ~4 seconds

print("Time seconds ",Date().timeIntervalSince1970)
for i in 0..<9999 {
    let nowDate = Calendar.current.date(bySettingHour: 0, minute: 0, second: 0, of: Date())!
}
print("Time seconds ",Date().timeIntervalSince1970)// For loop took 4 seconds

有什么方法可以减少编译时间?

Is there any way to reduce compile time ?

答

您不能在Playground中测试性能，并且大多数情况下不能编译性能.游乐场要做很多额外的工作，以在右侧栏中显示(9999次)".游乐场也实际上没有单独的编译"步骤，您可以将其与执行分开.而且他们不会优化代码.您无法在Playground中评估任何性能.

You can't test performance in a Playground, and most of all not compile performance. Playgrounds do a lot of extra work to display "(9999 times)" in the right-hand column. Playgrounds also don't really have a separate "compile" step that you can separate from execution. And they don't optimize the code. There's no part of performance that you can evaluate in a Playground.

当我用swiftc编译它时，它花费不到半秒钟的时间.它运行不到一秒钟.

When I compile this with swiftc it takes less than half a second. It runs in less than a second.

Calendar.current.date(bySettingHour编译需要花费很长时间

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