Operator '?:' has lower precedence than '*'; '*' will be evaluated first

1.项目中用宏的时候，遇到如下警告

 Operator ‘?:‘ has lower precedence than ‘*‘; ‘*‘ will be evaluated first

2.错误原因

*操作符的优先级比 ?符号优先级低，会先*运算，结果也许就并不是自己需要的

类似此错误一般都与优先级有关

3.解决方案（示例）

#define app_rate (UI_USER_INTERFACE_IDIOM() == UIUserInterfaceIdiomPad)? screen_width/768 : screen_width/375

    self.lv1.sd_layout
    .rightSpaceToView(self.bg_image,app_rate*205)
    .topSpaceToView(self.bg_image, app_rate*203)
    .heightIs(82*app_rate)
    .widthIs(160*app_rate);

app_rate写在*前面是可以的，或者给宏定义加个括号

#define app_rate ((UI_USER_INTERFACE_IDIOM() == UIUserInterfaceIdiomPad)? screen_width/768 : screen_width/375)