如何将UInt64转换为Int64？

Question

在此函数调用的第二个参数：

dispatch_time(DISPATCH_TIME_NOW, NSEC_PER_SEC) 

导致编译器错误：

'UInt64' is not convertible to 'Int64' 

斯威夫特参考：

func dispatch_time(when: dispatch_time_t, delta: Int64) -> dispatch_time_t 

var NSEC_PER_SEC: UInt64 { get } /* nanoseconds per second */ 

Answer 1

参见：How do you cast a UInt64 to an Int64?这个问题不显示当谷歌搜索编译错误：'UInt64' is not convertible to 'Int64'