Swift 随笔

tableView刷新周期

CATransaction.begin()
CATransaction.setCompletionBlock {
  self.tableView.reloadData()
}
self.tableView.beginUpdates()
self.tableView.deleteRows(at: [(NSIndexPath(row: idx, section: 0) as IndexPath)], with: .left)
self.tableView.endUpdates()
CATransaction.commit()

UITextField 限制字数

@objc func textFieldDidChange(_ textfield: UITextField) {
    guard let _ = textfield.markedTextRange else {
        let cursorPostion = textfield.offset(from: textfield.endOfDocument, to: textfield.selectedTextRange!.end)
        if textfield.text!.count > textfield.tag {
            textfield.text = String(textfield.text!.prefix(textfield.tag))
        }
        let targetPosion = textfield.position(from: textfield.endOfDocument, offset: cursorPostion)!
        textfield.selectedTextRange = textfield.textRange(from: targetPosion, to: targetPosion)
        return
    }
}

图片添加图片水印

extension UIImage{
    
    enum WaterMarkCorner{
        case TopLeft
        case TopRight
        case BottomLeft
        case BottomRight
    }
    
    func waterMarkedImage(waterMarkImage: UIImage,
                          corner: WaterMarkCorner = .BottomRight,
                          margin: CGPoint = CGPoint(x: 30, y: 47),
                          alpha: CGFloat = 1,
                          size: CGSize) -> UIImage {
        
        var markFrame = CGRect(x:0, y: 0, width: size.width, height: size.height)
        let imageSize = self.size
        
        switch corner{
        case .TopLeft:
            markFrame.origin = margin
        case .TopRight:
            markFrame.origin = CGPoint(x: imageSize.width - waterMarkImage.size.width - margin.x,
                                       y: margin.y)
        case .BottomLeft:
            markFrame.origin = CGPoint(x: margin.x,
                                       y: imageSize.height - waterMarkImage.size.height - margin.y)
        case .BottomRight:
            markFrame.origin = CGPoint(x: imageSize.width - waterMarkImage.size.width - margin.x,
                                       y: imageSize.height - waterMarkImage.size.height - margin.y)
        }
        
        UIGraphicsBeginImageContext(imageSize)
        self.draw(in: CGRect(x: 0, y:0, width: imageSize.width, height: imageSize.height))
        waterMarkImage.draw(in: markFrame, blendMode: .normal, alpha: alpha)
        let waterMarkedImage = UIGraphicsGetImageFromCurrentImageContext()
        UIGraphicsEndImageContext()
        
        return waterMarkedImage!
    }
}

绘制虚线

extension UIView {
    /// 绘制虚线
    func drawDashLine(_ strokeColor: UIColor, lineWidth: CGFloat = 1, lineLength: Int = 10, lineSpacing: Int = 5) {
        let shapeLayer:CAShapeLayer = CAShapeLayer()
        shapeLayer.bounds = self.bounds
        shapeLayer.position = CGPoint(x: self.frame.width / 2, y: self.frame.height / 2)
        shapeLayer.fillColor = UIColor.clear.cgColor
        shapeLayer.strokeColor = strokeColor.cgColor
        shapeLayer.lineWidth = lineWidth
        shapeLayer.lineJoin = CAShapeLayerLineJoin.round
        shapeLayer.lineDashPhase = 0
        shapeLayer.lineDashPattern = [NSNumber(value: lineLength), NSNumber(value: lineSpacing)]
        
        let path:CGMutablePath = CGMutablePath()
        path.move(to: CGPoint(x: 0, y: 10))
        path.addLine(to: CGPoint(x: self.frame.width, y: 10))
        shapeLayer.path = path
        
        self.layer.addSublayer(shapeLayer)
    }
}

Double 小数点后保存几位

extension Double {
    func truncate(places: Int) -> Double {
        let divisor = pow(10.0, Double(places))
        return Double(Int(self * divisor)) / divisor
    }
}

颜色 转 image

    /// 颜色 转 image
    /// - Parameters:
    ///   - color: 颜色
    ///   - viewSize: size
    func imageFromColor(color: UIColor, viewSize: CGSize) -> UIImage {
        let rect: CGRect = CGRect(x: 0, y: 0, width: viewSize.width, height: viewSize.height)
        UIGraphicsBeginImageContext(rect.size)
        let context: CGContext = UIGraphicsGetCurrentContext()!
        context.setFillColor(color.cgColor)
        context.fill(rect)
        let image = UIGraphicsGetImageFromCurrentImageContext()
        UIGraphicsGetCurrentContext()
        return image!
    }

禁止右划返回怎么都不管用试试这个

override func viewWillAppear(_ animated: Bool) {
        super.viewWillAppear(animated)
        let target = self.navigationController?.interactivePopGestureRecognizer?.delegate
        let pan = UIPanGestureRecognizer(target: target, action: nil)
        self.view.addGestureRecognizer(pan)
    }