我有这个正则表达式：
var match = /^[\s\S]*(?:^|\r?\n)\s*(\d+)(?![\s\S]*(\r?\n){2})/m.exec(val);
var before = Number(match[1]) + 1;
现在没有任何匹配，我遇到了这个错误：
未捕获的TypeError：无法读取属性＆＃39; 1＆＃39;为null
我该如何解决？我想我必须设置NULL而不是match[1]。
答案 0 :(得分：3)
试试这个：
@IBAction func startBubble(sender: AnyObject) {
//var bubble = UIView()
let screenSize = UIScreen.mainScreen().bounds
let screenWidth = screenSize.width
let screenHeight = screenSize.height
// Animation parameters
let duration : NSTimeInterval = 9.0
var delay : NSTimeInterval = 1.0
var minimumDelay : NSTimeInterval = 3.0
let factor : CGFloat = 1.75
let opacity : CGFloat = 0.3
let options: UIViewAnimationOptions = [.CurveEaseIn, .AllowUserInteraction]
for bubbleNumber in 1...10 {
// Bubble size
let bubbleWidth : CGFloat = CGFloat(arc4random_uniform(40) + 130)
let bubbleHeight = bubbleWidth
// Bubble start position
let startPosition : CGFloat = CGFloat(arc4random_uniform(UInt32(screenWidth - bubbleWidth)))
// Bubble delay
if bubbleNumber > 1 {
minimumDelay = minimumDelay + NSTimeInterval(3.0)
delay = minimumDelay + (NSTimeInterval(arc4random_uniform(1000)) / 1000)
}
let bubble = UIImageView(frame: CGRectMake(startPosition, screenHeight, bubbleWidth, bubbleHeight))
// Bubble definition
bubble.image = UIImage(named: "bubble.png")
bubble.tag = bubbleNumber
bubble.userInteractionEnabled = true
bubble.addGestureRecognizer(UITapGestureRecognizer(target: self, action: "openBubble:"))
self.view.addSubview(bubble)
UIView.animateWithDuration(duration, delay: delay, options: options, animations: {
bubble.frame = CGRectMake(startPosition, 1, factor*bubbleWidth, factor*bubbleHeight)
bubble.alpha = opacity
}, completion: { animationFinished in
bubble.alpha = 0.1
bubble.removeFromSuperview()
})
}
}
func openBubble(sender:UITapGestureRecognizer){
let tappedBubble = sender.view!
print(tappedBubble.tag)
}
如果找不到匹配项，则会将var before = ( match === null ) ? 1 : match[1]设置为before，否则应返回正确的匹配项。
答案 1 :(得分：1)
您应首先预先形成一个匹配项以查看是否存在匹配项。
var m = /^[\s\S]*(?:^|\r?\n)\s*(\d+)(?![\s\S]*(\r?\n){2})/m.exec(val);
var before = m === null ? 0 : +m[1]+1;
/* notice the Array returned by match can be immediately accessed then
cast to a number with + in front */