chenqipc的专栏

刚接触swift，做值判断是否为空的时候，报了这个错误，Type "String" does not confirm to protocol "BooleanType"let s_num1 = "123";let s_num2 = s_num1.toInt()var s_num4 = 123;if (s_num1 != nil) {println("true")} //这行报错if

control reaches end of non-void function控制到达非void函数的结尾。也就是说非void函数没有返回值。ß