如何在iOS Swift 3中使用防护和条件？

我想得到函数的结果并将其设置在另一个变量（let或var）中，然后用如下条件检查它：

guard galleryArr:Array<UIImage> = fetchGalleryImages() , galleryArr.count  != 0 {

}else{

}  

guard galleryArr:Array=fetchgallerymages（），galleryArr.count！=0 {
}否则{
}  

请告诉我解决此问题的正确方法。

尝试以下方法：

func doSomething() -> Int? {
    guard let galleryArr = fetchGalleryImages(), galleryArr.count != 0 else {
        // you must return from doSomething in here, be it by throwing
        // a fatalError(), return nil, or some other value to indicate
        // that the call has failed
        return nil
    }

    // proceed with the function
    return ...
}

试试这个：

func doSomething() -> Int? {
    guard let galleryArr = fetchGalleryImages(), galleryArr.count != 0 else {
        // you must return from doSomething in here, be it by throwing
        // a fatalError(), return nil, or some other value to indicate
        // that the call has failed
        return nil
    }

    // proceed with the function
    return ...
}

---

Swift 3.0

您可以在以下情况下使用用户防护和where：

但必须是

fetchGalleryImages（）

return

optional

value

guard let galleryArr = fetchGalleryImages(), galleryArr.count > 0 else { 
 //What ever condition you want to do on fail or simply return 
}

---

Swift 3.0

您可以在以下情况下使用用户防护和where：

但必须是

fetchGalleryImages（）

return

optional

value

guard let galleryArr = fetchGalleryImages(), galleryArr.count > 0 else { 
 //What ever condition you want to do on fail or simply return 
}

fetchGalleryImages（）是如何定义的？它返回数组还是可选数组？fetchGalleryImages（）是如何定义的？它返回数组还是可选数组？