TableView Array Map - ios

Question

My code is swift 3 and has create two array in TableView, get JSON data into Array, if I map this two array will get error index out of range, How to right map Array ?
func trainType() {
do {
/// 取得所有列車車種資料
let trainTypeUrl = URL(string: "http://ptx.transportdata.tw/MOTC/v2/Rail/TRA/TrainClassification?$format=JSON")
let trainTypeData = try? Data(contentsOf: trainTypeUrl!)
let trainTypeJson = try? JSONSerialization.jsonObject(with: trainTypeData!, options: .mutableContainers)
if let trainTypes = trainTypeJson as? [[String : AnyObject]] {
for dataTrainType in trainTypes {
trainTypeArray.append(dataTrainType as AnyObject)
}
}
}
self.tableView.reloadData()
}
func trainInOutstatusData() {
do {
let trainStatusUrl = URL(string: "http://ptx.transportdata.tw/MOTC/v2/Rail/TRA/LiveBoard?$format=JSON")
let trainInOutstatusData = try? Data(contentsOf: trainStatusUrl!)
let trainInOutStatusjson = try? JSONSerialization.jsonObject(with: trainInOutstatusData!, options: .mutableContainers)
if let InOutStatus = trainInOutStatusjson as? [[String : AnyObject]] {
for dataInOutStatus in InOutStatus {
trainStatusArray.append(dataInOutStatus as AnyObject!)
}
}
}
self.tableView.reloadData()
}
map array
let stationClassID = trainStatusArray[indexPath.row]["TrainClassificationID"] as? String
let trainClassID = trainTypeArray[indexPath.row]["TrainClassificationID"] as? String
if stationClassID == trainClassID {
if let trainTypeID = trainTypeArray[indexPath.row]["TrainClassificationID"] as? [String : Any] {
let ZHtw = trainTypeID["Zh_tw"] as? String
cell.stationTrainClassID.text = ZHtw
}
}

Answer 1

Since you have different data counts in both array, you can't do as you tried. Because consider you have 5 count in trainStatusArray and 3 count trainTypeArray, your current indexPath.row is 4. Then
let stationClassID = trainStatusArray[4]["TrainClassificationID"] as? String // You will get some value here.
let trainClassID = trainTypeArray[4]["TrainClassificationID"] as? String // Here app will crash because, total count is 3 in but you are trying to access element at index 4.
Solution:
You can give an array which have higher count as data source to tableView, then you can use for loop in cellForRowAtIndexpath to check the values are matching or not.
func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell {
let stationClassID = trainStatusArray[indexPath.row]["TrainClassificationID"] as? String
for trainType in trainTypeArray {
let trainClassID = trainType["TrainClassificationID"] as? String
if stationClassID == trainClassID {
if let trainTypeID = trainTypeArray[indexPath.row]["TrainClassificationID"] as? [String : Any] {
let ZHtw = trainTypeID["Zh_tw"] as? String
cell.stationTrainClassID.text = ZHtw
}
}
}
}
Thanks.