Swift 2.0 新增功能;尝试学习它,对动画感兴趣,并尝试编写一些代码来一次在屏幕上显示一个字符的消息。
我写了这个,它有效,但我忍不住,但我不能用 CALayers 和/或 alpha 值做一些事情吗?或者一些有生命力的小发明,一些更快速的值得的东西;这感觉和看起来有点笨重,确实是 1977 年的风格。
import UIKit
class ViewController: UIViewController {
override func viewDidLoad() {
super.viewDidLoad()
// Do any additional setup after loading the view, typically from a nib.
let supertext = "A long time ago, in a galaxy far, far away ..."
let round = supertext.characters.count
for i in 0...round {
let delay = Double(i)/10
let subtext = supertext[supertext.startIndex..<supertext.startIndex.advancedBy(i)]
NSTimer.scheduledTimerWithTimeInterval(delay, target: self, selector: "ghostText:", userInfo: ["theText" :subtext], repeats: false)
}
}
var view3:UITextView = UITextView()
func ghostText(timer:NSTimer) {
view3.removeFromSuperview()
let userInfo = timer.userInfo as! Dictionary<String, AnyObject>
let tempText:NSString = (userInfo["theText"] as! NSString)
print(tempText)
let font = UIFont(name: "Georgia", size: 18.0) ?? UIFont.systemFontOfSize(18.0)
let textFont = [NSFontAttributeName:font]
let subChararacter = NSAttributedString(string: String(tempText), attributes: textFont)
view3.frame = CGRect(x: 100, y: 120, width: CGRectGetWidth(self.view.frame), height: CGRectGetWidth(self.view.frame)-20)
view3.attributedText = subChararacter
self.view.addSubview(view3)
}
最佳答案
我认为 Swiftworthy 是主观的,但这里有另一个实现,它基于您的代码当前的工作方式,将 NSTimer 包装在 Swift 类中。
class Timer {
typealias TimerFunction = (Int)->Bool
private var handler: TimerFunction
private var i = 0
init(interval: NSTimeInterval, handler: TimerFunction) {
self.handler = handler
NSTimer.scheduledTimerWithTimeInterval(interval, target: self, selector: "timerFired:", userInfo: nil, repeats: true)
}
@objc
private func timerFired(timer:NSTimer) {
if !handler(i++) {
timer.invalidate()
}
}
}
class ViewController: UIViewController {
let text: NSAttributedString = {
let font = UIFont(name: "Georgia", size: 18.0) ?? UIFont.systemFontOfSize(18.0)
return NSAttributedString(string: "A long time ago, in a galaxy far, far away ...", attributes: [NSFontAttributeName: font])
}()
override func viewDidLoad() {
super.viewDidLoad()
let textView = UITextView(frame: CGRect(x: 100, y: 120, width: CGRectGetWidth(self.view.frame), height: CGRectGetWidth(self.view.frame)-20))
self.view.addSubview(textView)
let _ = Timer(interval: 0.1) {i -> Bool in
textView.attributedText = self.text.attributedSubstringFromRange(NSRange(location: 0, length: i+1))
return i + 1 < self.text.string.characters.count
}
}
}
关于ios - 在 swift 2.0 中一次显示一个字符的文本,我们在Stack Overflow上找到一个类似的问题: https://stackoverflow.com/questions/33858956/