swift 文字验证码

这个demo的主要功能是用于防止有人浪用接口，频繁的去请求接口。实现的主要原理如下：

1.创建一个用来验证的字符串

func getAuthcode() {

codeArray = ["0","1","2","3","4","5","6","7","8","9","A","B","C","D","E","F","G","H","I","J","K","L","M","N","O","P","Q","R","S","T","U","V","W","X","Y","Z","a","b","c","d","e","f","g","h","i","j","k","l","m","n","o","p","q","r","s","t","u","v","w","x","y","z"]

for _ in 0..<6//需要多少个字符来验证

{

let num = codeArray.count-1

let y = Int(arc4random_uniform(UInt32(num)))

let tempStr = codeArray[y]

if codeString == nil {

codeString =  tempStr

}else{

codeString = codeString! +  tempStr

}}}

2.为这个字符串创建一个视图 

override func draw(_ rect: CGRect) {

super.draw(rect)

self.backgroundColor = UIColor.init(red: CGFloat(Double(arc4random()%256)/256.0) , green:  CGFloat(Double(arc4random()%256)/256.0) , blue:  CGFloat(Double(arc4random()%256)/256.0) , alpha: 1.0)

let cSize = ("A" as NSString).size(attributes: [NSFontAttributeName:UIFont.systemFont(ofSize: 20)])

let width = rect.size.width/CGFloat((codeString! as NSString).length) - cSize.width

let height = rect.size.height - cSize.height

var point:CGPoint?

var x:CGFloat = 0.0

var y:CGFloat = 0.0

for index in 0..<(codeString! as NSString).length {

x = CGFloat(arc4random_uniform(UInt32(width))) + rect.size.width/CGFloat((codeString! as NSString).length)*CGFloat(index)

y = CGFloat(arc4random_uniform(UInt32(height)))

point = CGPoint.init(x: x, y: y)

let  c = (codeString! as NSString).character(at: index)

let textC:String = String(Character(UnicodeScalar(c)!))

(textC as NSString).draw(at: point!, withAttributes: [NSFontAttributeName:UIFont.systemFont(ofSize: CGFloat(arc4random_uniform(UInt32(5)) + 15))])

}

let context = UIGraphicsGetCurrentContext()

context?.setLineWidth(1.0)

for _ in 0..<5//线条数量

{

let color =  UIColor.init(red: CGFloat(Double(arc4random()%256)/256.0) , green:  CGFloat(Double(arc4random()%256)/256.0) , blue:  CGFloat(Double(arc4random()%256)/256.0) , alpha: 1.0)

context?.setStrokeColor(color.cgColor)

x = CGFloat(arc4random_uniform(UInt32(rect.size.width)))

y = CGFloat(arc4random_uniform(UInt32(rect.size.height)))

context?.move(to: CGPoint.init(x: x, y: y))

x = CGFloat(arc4random_uniform(UInt32(rect.size.width)))

y = CGFloat(arc4random_uniform(UInt32(rect.size.height)))

context?.addLine(to: CGPoint.init(x: x, y: y))

context?.strokePath()

}}

3.为这个视图添加触摸手势，可以让其更换视图

override func touchesBegan(_ touches: Set, with event: UIEvent?) {

codeString = nil

self.getAuthcode()

self.setNeedsDisplay()

}

4》最后的效果如下：