比较值时更改视图颜色

Question

我创建了一个用作背景的视图，我想在标签文本大于或小于变量数时更改其颜色。脚本没问题，但颜色没有变化。

提前致谢。

导入 UIKit

类 ViewController: UIViewController, UITextFieldDelegate {

@IBOutlet weak var localName: UITextField!

@IBOutlet weak var localNameLabel: UILabel!

@IBOutlet weak var localTemp: UILabel!

@IBAction func getData(sender: AnyObject) {
    getWeatherData("http://api.openweathermap.org/data/2.5/weather?q=" + localName.text! + "")
}


@IBOutlet weak var fundo: UIView!

override func viewDidLoad() {
    super.viewDidLoad()
    getWeatherData("http://api.openweathermap.org/data/2.5/weather?q=London")
    // Do any additional setup after loading the view, typically from a nib.
}

override func didReceiveMemoryWarning() {
    super.didReceiveMemoryWarning()
    // Dispose of any resources that can be recreated.
}


func getWeatherData(urlString: String){
    let url = NSURL (string: urlString)

    let task = NSURLSession.sharedSession().dataTaskWithURL(url!) { (data, response, error) in
        dispatch_async(dispatch_get_main_queue(), {
            self.setLabels(data!)
        })
    }

    task.resume()
}

func setLabels(weatherData: NSData) {

    do {
        let json = try NSJSONSerialization.JSONObjectWithData(weatherData, options:NSJSONReadingOptions.MutableContainers) as! NSDictionary
        print(json)

        //localNameLabel.text = json[("name")] as? String
        if let name = json[("name")] as? String {
            localNameLabel.text = name
        }

        if let main = json[("main")] as? NSDictionary {
            if let temp = main[("temp")] as? Double {
                //convert kelvin to celsius
                let ft = (temp - 273.15)

                let myString = ft.description

                localTemp.text = myString

                self.changeColor()

            }
        }


    } catch let error as NSError {
        print(error)
    }

var number : Float
func changeColor(){

    number = 19.0

    if(Float(localTemp.text!) < number){
        fundo.backgroundColor = .blueColor()
    }else{
        fundo.backgroundColor = .orangeColor()
        }
    }

}

}

编辑后发布整个脚本

Answer 1

在您的视图控制器中，您需要添加 UITextFieldDelegate 这将允许您访问与您的文本字段相关的方法。视图控制器的顶部应如下所示：

class ViewController: UIViewController,UITextFieldDelegate  //set delegate to class 

然后，您需要在 viewDidLoad 中将文本字段的委托设置为 self，并为文本字段更改时添加一个目标：

override func viewDidLoad() {
    super.viewDidLoad()
    localTemp.delegate = self     //set delegate to this vc
    localTemp.addTarget(self, action: "textFieldDidChange:", forControlEvents: UIControlEvents.EditingChanged)
}

然后你可以实现这个方法，它会在每次按键时运行，你需要像上面那样调用你的 changeColor() 方法：

func textFieldDidChange(textField: UITextField) {
    self.changeColor()
}