当在Swift中编码时，什么是`？`或者`：` [英] What is the `?` is or the `:` at the equation when coding in Swift

问题描述

我在臭名昭着的 SevenSwitch 课程中遇到了一行代码。

I have ran into a line of code in the infamous SevenSwitch class.

以下是行...

backgroundView.layer.cornerRadius = self.isRounded ? frame.size.height * 0.4 : 2

我不明白？或等式结束时的：。有人可以解释这些是什么意思以及如何使用它们吗？

I don't understand what the ? is or the : at the end of the equation. Could someone please explain what these mean and how they are used?

推荐答案

运营商可以是一元，二元或三元：

Operators can be unary, binary, or ternary:

这是三元运营商在三个目标上运作。与C一样，Swift只有一个三元运算符，即三元条件运算符（a？b：c）。

This is Ternary operators operate on three targets. Like C, Swift has only one ternary operator, the ternary conditional operator (a ? b : c).

来自Apple Documents 基本运算符

From Apple Documents Basic Operators

三元条件运算符

三元条件运算符是一个特殊的运算符，有三个
的部分，它采用了形式问题？回答1：回答2。它是
的快捷方式，用于根据
问题是true还是false来评估两个表达式中的一个。如果问题为真，则评估answer1
并返回其值;否则，它会评估answer2并返回其
值。

The ternary conditional operator is a special operator with three parts, which takes the form question ? answer1 : answer2. It is a shortcut for evaluating one of two expressions based on whether question is true or false. If question is true, it evaluates answer1 and returns its value; otherwise, it evaluates answer2 and returns its value.

根据您的问题如果 isRound 为真，然后角落无线电 frame.size.height 否则为2。

As per your question if isRound is true then corner radios is frame.size.height else it's 2.

如同条件：

if(self.isRounded){
    backgroundView.layer.cornerRadius = frame.size.height * 0.4
}
else{
    backgroundView.layer.cornerRadius = 2.0
}

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