Swift 尝试从字符串中检索随机字母时出现分段错误
我有这个功能:Swift 尝试从字符串中检索随机字母时出现分段错误,swift,string,swift3,segmentation-fault,arc4random,Swift,String,Swift3,Segmentation Fault,Arc4random,我有这个功能: func getRandomLetter() -> String { let len = allPossibleLetters.characters.count let r = arc4random_uniform(UInt32(len)) let index = allPossibleLetters.index (allPossibleLetters.startIndex, offsetBy: r) return String(allPos
func getRandomLetter() -> String {
let len = allPossibleLetters.characters.count
let r = arc4random_uniform(UInt32(len))
let index = allPossibleLetters.index (allPossibleLetters.startIndex, offsetBy: r)
return String(allPossibleLetters[index])
}
但是,在尝试编译时,我不断遇到以下错误:
Command failed due to signal: Segmentation fault: 11
当我将整数硬编码到offsetBy参数中时,它可以正常工作:
let index = allPossibleLetters.index (allPossibleLetters.startIndex, offsetBy: 11)
// returns a letter as expected
知道是什么原因吗?找到了答案。改变
let r = arc4random_uniform(UInt32(len))
到
现在它工作正常。似乎是传递了错误类型的问题:
let index = allPossibleLetters.index(allPossibleLetters.startIndex, offsetBy: Int(r))
对于这些分割问题,如果您单击该错误,它将带您查看错误详细信息。通常这个日志的结尾是最有趣的。
在你的情况下,它说:
在RangeText=“allPossibleLetters.index(allPossibleLetters.startIndex)处键入检查表达式时,
抵销人:r)
let index = allPossibleLetters.index(allPossibleLetters.startIndex, offsetBy: Int(r))