Swift 如何制作此UIButton';操作是否正确?
每次我运行这个swift游乐场(在Xcode上),最后一行都会出现一个错误,上面写着: 无法构造“PlaygroundView”,因为它没有可访问的初始值设定项 我在第4行还有另一个错误: 类“PlaygroundView”没有初始值设定项Swift 如何制作此UIButton';操作是否正确?,swift,uibutton,swift-playground,Swift,Uibutton,Swift Playground,每次我运行这个swift游乐场(在Xcode上),最后一行都会出现一个错误,上面写着: 无法构造“PlaygroundView”,因为它没有可访问的初始值设定项 我在第4行还有另一个错误: 类“PlaygroundView”没有初始值设定项 import UIKit import PlaygroundSupport class PlaygroundView:UIViewController { var introImage:UIImageView var introButton:UIButt
import UIKit
import PlaygroundSupport
class PlaygroundView:UIViewController {
var introImage:UIImageView
var introButton:UIButton
override func loadView() {
print("workspace started running.")
//Main Constant and Variable Declarations/General Setup
let mainView = UIView()
//Main View Modifications & styling
mainView.backgroundColor = UIColor.init(colorLiteralRed: 250, green: 250, blue: 250, alpha: 1)
func addItem(item: UIView) {
mainView.addSubview(item)
}
//Sub-Element Constant and Variable Declarations
introImage = UIImageView(frame: CGRect(x: 87.5, y: -300, width: 200, height: 200))
introImage.layer.borderColor = UIColor.black.cgColor
introImage.layer.borderWidth = 4
introImage.alpha = 0
introImage.transform = CGAffineTransform(rotationAngle: -90.0 * 3.14/180.0)
introImage.image = UIImage(named: "profile_pic.png")
introImage.image?.accessibilityFrame = introImage.frame
introImage.layer.cornerRadius = 100
addItem(item: introImage)
introButton = UIButton(frame: CGRect(x: 87.5, y: 900, width: 200, height: 30))
introButton.alpha = 0
introButton.setTitle("Tap to meet me", for: .normal)
introButton.titleLabel?.font = UIFont(name: "Avenir Book", size: 20)
introButton.backgroundColor = UIColor.black
introButton.layer.cornerRadius = 15
introButton.layer.borderWidth = 5
addItem(item: introButton)
introButton.addTarget(self, action: #selector(self.introButtonAction), for: .touchDown)
UIView.animate(withDuration: 1.5, delay: 1, options: .curveEaseInOut, animations: {
self.introImage.frame = CGRect(x: 87.5, y: 175, width: 200, height: 200)
self.introButton.frame = CGRect(x: 87.5, y: 400, width: 200, height: 30)
self.introImage.transform = CGAffineTransform(rotationAngle: 0.0 * 3.14/180.0)
self.introImage.alpha = 1
self.introButton.alpha = 1
}) { (mainAnimationComped) in
if mainAnimationComped == true {
print("introduction animation comped.")
}
}
}
//User Interface Actions
func introButtonAction() {
print("user interacted with user interface")
}
}
PlaygroundPage.current.liveView = PlaygroundView()
如何解决此问题?添加?在introImage和introButton之后
var introImage:UIImageView?
var introButton:UIButton?
加上?在introImage和introButton之后
var introImage:UIImageView?
var introButton:UIButton?
这是因为在Swift中,在代码中使用变量之前需要初始化变量。另一方面,因为在本例中,您在函数中显式地设置了它们,所以您可能会将它们声明为隐式展开的选项
var introImage:UIImageView!
var introButton:UIButton!
这应该可以在不改变代码中任何其他内容的情况下工作,因为在Swift中,在代码中使用变量之前需要初始化变量。另一方面,因为在本例中,您在函数中显式地设置了它们,所以您可能会将它们声明为隐式展开的选项
var introImage:UIImageView!
var introButton:UIButton!
这应该可以在不改变代码中任何其他内容的情况下工作谢谢!我完全按照你说的做了,而且成功了。还有这个网站:它帮助我完成了我的项目。谢谢!我完全按照你说的做了,而且成功了。还有这个网站:它帮助我完成了我的项目。