let age = -3 assert(age >= 0, "年龄不能小于0") // 条件为真,不执行断言 assert(false)
运行:
assertion failed: 年龄不能小于0: file/var/folders/gk/zc__29js08g1g03xrzgl8m1m0000gn/T/./lldb/5573/>playground390.swift, line 7
