Swift 三元條件運(yùn)算符

三元條件運(yùn)算符用于縮短if語句的代碼。愛掏網(wǎng) - it200.com它是一種特殊類型的操作符，由三部分組成:question ?answer1:answer2

它檢查問題是真還是假。愛掏網(wǎng) - it200.com如果問題為真，它將返回answer1的值;否則，它將返回answer2的值。愛掏網(wǎng) - it200.com

三元條件運(yùn)算符是以下代碼的簡寫形式:

if question {  
    answer1  
} else {  
    answer2  
} 

讓我們看一個三元條件運(yùn)算符的例子。愛掏網(wǎng) - it200.com在這個例子中，我們將計(jì)算表格行的高度。愛掏網(wǎng) - it200.com如果行有標(biāo)題，行高應(yīng)該比內(nèi)容高50點(diǎn);如果行沒有標(biāo)題，行高應(yīng)該比內(nèi)容高20點(diǎn)。愛掏網(wǎng) - it200.com

示例(不含三元條件運(yùn)算符)

let contentHeight = 40  
let hasHeader = true  
let rowHeight: Int  
if hasHeader {  
    rowHeight = contentHeight + 50  
} else {  
    rowHeight = contentHeight + 20  
}  
// rowHeight is equal to 90  

示例(使用三元條件運(yùn)算符)

let contentHeight = 40  
let hasHeader = true  
let rowHeight = contentHeight + (hasHeader ? 50 : 20)  
// rowHeight is equal to 90