循环处理时间过长答案

【问题标题】：Loop is taking too long to process循环处理时间过长
【发布时间】：2018-03-15 12:38:11
【问题描述】：

我正在使用以下代码将联系人数组排列在部分中（例如，前缀为“A”的联系人应显示在“A”部分下）。如果有 4-5 百个联系人，则处理需要 20 秒。

你能检查一下这里有什么问题吗？或任何替代品。

 let finalArr = NSMutableArray()

    for contactDetail in conatctsArr {

        let name = (contactDetail as! Dictionary)["givenName"] ?? ""// Getting First character of name
        var key = String()
        if name.characters.count > 0 {
            let index1 = name.index((name.startIndex), offsetBy: 1)
            key = name.substring(to: index1)
        }
        else {
            key = ""
        }

        // getting all contatcts starting with particular character
        let predicate=NSPredicate(format: "SELF.givenName beginswith[c] %@",key)

        let filteredArr = (conatctsArr as NSArray).filtered(using: predicate)

        var dic = Dictionary<String, Any>()
        dic["key"] = key
        dic["values"] = filteredArr

        if filteredArr.count > 0  && !(finalArr.contains(dic)) {
            finalArr.add(dic)
        }
    }

【问题讨论】：

标签： ios swift xcode performance memory

【解决方案1】：

在每个循环中处理后从数组中删除过滤后的元素可能会提高性能。试试：

    let finalArr = NSMutableArray()
    var processingArray = NSMutableArray(array:conatctsArr)

    while processingArray.count > 0 {
        let contactDetail = processingArray[0]
        let name = (contactDetail as! Dictionary)["givenName"] ?? ""
        var key = String()
        if name.characters.count > 0 {
            let index1 = name.index((name.startIndex), offsetBy: 1)
            key = name.substring(to: index1)
        }
        else {
            key = ""
        }

        let predicate=NSPredicate(format: "SELF.givenName beginswith[c] %@",key)
        let filteredArr = processingArray.filtered(using: predicate)

        if filteredArr.count > 0 {
            var dic = Dictionary<String, Any>()
            dic["key"] = key
            dic["values"] = filteredArr
            finalArr.add(dic)
        }

        processingArray.removeObjects(in: filteredArr)
    }

【讨论】：

【解决方案2】：

在您的代码中，对同一个键进行了多次过滤。试试看：

let finalArr = NSMutableArray()
    for contactDetail in conatctsArr 
{
    let keysArray = [“A”, “B”, “C”,…. “Z”]
    for key in keysArray
    {
        let predicate=NSPredicate(format: "SELF.givenName beginswith[c] %@",key)
        let filteredArr = (conatctsArr as NSArray).filtered(using: predicate)
        var dic = Dictionary<String, Any>()
        dic["key"] = key
        dic["values"] = filteredArr
        if filteredArr.count > 0) {
            finalArr.add(dic)
            }
    }
}

【讨论】：