如何在Swift UI中从字符串中获取子字符串? [英] How to get substring out of string in swift ui?

问题描述

在UIKit中，我使用相同的方法从长字符串中仅获取一部分，并且在那里工作.但是，它不能在快速的ui应用程序中工作.我想知道它是否不是字符串，而是其他东西.有谁知道更好的解决方案，只从长文本中获取一个短子字符串?

In UIKit I used the same method to get only one part out of a long string and there it worked. However it dosen't work in swift ui app. I have wondered if it might be that it is not a string, but something else. Does anyone know a better solution to only get a short substring out of the long text?

let url = URL(string: "https://midcdmz.nrel.gov/apps/spa.pl?syear=2020&smonth=1&sday=1&eyear=2020&emonth=1&eday=1&otype=0&step=60&stepunit=1&hr=12&min=0&sec=0&latitude=39.743&longitude=-105.178&timezone=-7.0&elev=1829&press=835&temp=10&dut1=0.0&deltat=64.797&azmrot=180&slope=0&refract=0.5667&field=0")

struct ContentView: View {
    
    
    var html = try! String(contentsOf: url!, encoding: String.Encoding.ascii)
    
    let leftSideOfTheValue = "1/1/2020,0:00:00,"
    
    let rightSideOfTheValue = "1/1/2020,1:00:00,"
    
    guard let leftRange = html.range(of: leftSideOfTheValue) else {
        print("cant find left range")
        return
    }
    
    guard let rightRange = html.range(of: rightSideOfTheValue) else {
        print("cant find right range")
        return
    
    let rangeOfTheValue = leftRange.upperBound..<rightRange.lowerBound
    
    let elevationInfo = (html[rangeOfTheValue])
    
    var body: some View {
        Text(elevationInfo)
                
    }

推荐答案

可能的解决方案(使用功能):

Possible solution (Using function):

struct ContentView: View {
    private let url = URL(string: "https://midcdmz.nrel.gov/apps/spa.pl?syear=2020&smonth=1&sday=1&eyear=2020&emonth=1&eday=1&otype=0&step=60&stepunit=1&hr=12&min=0&sec=0&latitude=39.743&longitude=-105.178&timezone=-7.0&elev=1829&press=835&temp=10&dut1=0.0&deltat=64.797&azmrot=180&slope=0&refract=0.5667&field=0")
    
    var body: some View {
        Text(self.getSubstring(from: url))
        
    }
    
    private func getSubstring(from url: URL?) -> String {
        guard let url = url else {
            return ""
        }
        
        let html = try! String(contentsOf: url, encoding: String.Encoding.ascii)
        let leftSideOfTheValue = "1/1/2020,0:00:00,"
        
        let rightSideOfTheValue = "1/1/2020,1:00:00,"
        
        guard let leftRange = html.range(of: leftSideOfTheValue) else {
            print("cant find left range")
            return ""
        }
        
        guard let rightRange = html.range(of: rightSideOfTheValue) else {
            print("cant find right range")
            return ""
        }
        
        let rangeOfTheValue = leftRange.upperBound..<rightRange.lowerBound
        
        return String(html[rangeOfTheValue])
    }
}

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