How to loop through an array of objects in swift

Question

I m trying to access the url of an object stored in an array  but I m getting errors no matters what methods I m using   let userPhotos   currentUser  photos      for var i   0  i  lt  userPhotos  count     i           let url   userPhotos i  url         Here I get      Could not find member  url    and with a foreach    for photo in userPhotos            Utils getImageAsync photo url   completion     img  UIImage   - gt     in                     I get         ModelAttachment    does not have a member named  Generator    My array is var photos  Array lt ModelAttachment gt   and my ModelAttachment looks like this    class ModelAttachment  Model   var id  String  var url  String  var thumb  String      Any pointers to what I m doing wrong would be great

User · Answer

You can try using the simple NSArray in syntax for iterating over the array in swift which makes for shorter code. The following is working for me:

class ModelAttachment {
    var id: String?
    var url: String?
    var thumb: String?
}

var modelAttachementObj = ModelAttachment()
modelAttachementObj.id = "1"
modelAttachementObj.url = "http://www.google.com"
modelAttachementObj.thumb = "thumb"

var imgs: Array<ModelAttachment> = [modelAttachementObj]

for img in imgs  {
    let url = img.url
    NSLog(url!)
}

See docs here

User · Answer

The photos property is an optional array and must be unwrapped before accessing its elements  the same as you do to get the count property of the array    for var i   0  i  lt  userPhotos  count     i       let url   userPhotos  i  url

User · Answer

Unwrap and downcast the objects to the right type  safely  with if let  before doing the iteration with a simple for in loop   if let currentUser   currentUser       let photos   currentUser photos as   ModelAttachment         for object in photos           let url   object url           There s also guard let else instead of if let if you prefer having the result available in scope   guard let currentUser   currentUser       let photos   currentUser photos as   ModelAttachment  else           break or return      now  photos  is available outside the guard for object in photos       let url   object url

User · Answer

Your userPhotos array is option-typed  you should retrieve the actual underlying object with    if you want an error in case the object isn t there  or    if you want to receive nil in url    let userPhotos   currentUser  photos  for var i   0  i  lt  userPhotos  count     i       let url   userPhotos  i  url     But to preserve safe nil handling  you better use functional approach  for instance  with map  like this   let urls   userPhotos  map   0 url

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