Ios 在Swift中实现UILabel动画效果的最佳方法？

我对Swift中的动画制作非常陌生，我有一个想法，但我想看看其他人会怎么做-

我正在尝试创建这样一种效果：当用户进入搜索栏时，搜索栏的占位符文本缩小并向上移动到搜索字段上方，并更改为不同的颜色。像这样：

当你点击用户名时

如果我将uilabel放置在搜索栏上，并在输入搜索者时缩放此标签，我不确定输入搜索栏是否会注册，因为uilabel将位于其上方

我通常会尝试复制这些文本字段。我将如何开始创建此动画？或者甚至在我的搜索栏中添加一个底部边框

布里杰：

//
//  Makestagram-Bridging-Header.h
//  round
//
//  Created by Skylar Thomas on 6/24/16.
//  Copyright © 2016 Make School. All rights reserved.
//

#ifndef Makestagram_Bridging_Header_h
#define Makestagram_Bridging_Header_h

#import "PureLayout.h"

#endif /* Makestagram_Bridging_Header_h */

错误：

我的项目：

---

您可以这样尝试：

要创建动画，请执行以下操作：

将标签放置在文本字段上，并将轻触手势识别器添加到标签。将标签缩放到其位置，并在点击标签时将文本字段设置为第一响应者

要创建底部边框，请执行以下操作：

根据需要，在文本字段下方添加高度为1或2像素的UIView/UIImageView。并为文本字段设置无边框样式

---

要更改带有颜色的图标，请尝试。通过这种方式，您只需传递字符串名称即可将图标更改为彩色图标。

这是关于一个优秀项目的源代码，该项目完全实现了您的搜索：

    public enum EGFloatingTextFieldValidationType {
        case Email
        case Number
    }

    public class EGFloatingTextField: UITextField {


        private typealias EGFloatingTextFieldValidationBlock = ((text:String,inout message:String)-> Bool)!

        public var validationType : EGFloatingTextFieldValidationType!


        private var emailValidationBlock  : EGFloatingTextFieldValidationBlock
        private var numberValidationBlock : EGFloatingTextFieldValidationBlock


        let kDefaultInactiveColor = UIColor(white: CGFloat(0), alpha: CGFloat(0.54))
        let kDefaultActiveColor = UIColor.blueColor()
        let kDefaultErrorColor = UIColor.redColor()
        let kDefaultLineHeight = CGFloat(22)
        let kDefaultLabelTextColor = UIColor(white: CGFloat(0), alpha: CGFloat(0.54))


        public var floatingLabel : Bool!
        var label : UILabel!
        var labelFont : UIFont!
        var labelTextColor : UIColor!
        var activeBorder : UIView!
        var floating : Bool!
        var active : Bool!
        var hasError : Bool!
        var errorMessage : String!



        required public init(coder aDecoder: NSCoder) {
            super.init(coder: aDecoder)
            self.commonInit()
        }


        override public init(frame: CGRect) {
            super.init(frame: frame)
            self.commonInit()
        }

        func commonInit(){

            self.emailValidationBlock = ({(text:String, inout message: String) -> Bool in
                var emailRegex = "[A-Z0-9a-z._%+-]+@[A-Za-z0-9.-]+\\.[A-Za-z]{2,6}"

                var emailTest = NSPredicate(format:"SELF MATCHES %@" , emailRegex)

                var  isValid = emailTest.evaluateWithObject(text)
                if !isValid {
                    message = "Invalid Email Address"
                }
                return isValid;
            })
            self.numberValidationBlock = ({(text:String,inout message: String) -> Bool in
                var numRegex = "[0-9.+-]+";
                var numTest = NSPredicate(format:"SELF MATCHES %@" , numRegex)

                var isValid =  numTest.evaluateWithObject(text)
                if !isValid {
                    message = "Invalid Number"
                }
                return isValid;

            })
            self.floating = false
            self.hasError = false

            self.labelTextColor = kDefaultLabelTextColor
            self.label = UILabel(frame: CGRectZero)
            self.label.font = self.labelFont
            self.label.textColor = self.labelTextColor
            self.label.textAlignment = NSTextAlignment.Left
            self.label.numberOfLines = 1
            self.label.layer.masksToBounds = false
            self.addSubview(self.label)


            self.activeBorder = UIView(frame: CGRectZero)
            self.activeBorder.backgroundColor = kDefaultActiveColor
            self.activeBorder.layer.opacity = 0
            self.addSubview(self.activeBorder)

            self.label.autoAlignAxis(ALAxis.Horizontal, toSameAxisOfView: self)
            self.label.autoPinEdge(ALEdge.Left, toEdge: ALEdge.Left, ofView: self)
            self.label.autoMatchDimension(ALDimension.Width, toDimension: ALDimension.Width, ofView: self)
            self.label.autoMatchDimension(ALDimension.Height, toDimension: ALDimension.Height, ofView: self)

            self.activeBorder.autoPinEdge(ALEdge.Bottom, toEdge: ALEdge.Bottom, ofView: self)
            self.activeBorder.autoPinEdge(ALEdge.Left, toEdge: ALEdge.Left, ofView: self)
            self.activeBorder.autoPinEdge(ALEdge.Right, toEdge: ALEdge.Right, ofView: self)
            self.activeBorder.autoSetDimension(ALDimension.Height, toSize: 2)

            NSNotificationCenter.defaultCenter().addObserver(self, selector: Selector("textDidChange:"), name: "UITextFieldTextDidChangeNotification", object: self)
        }
        public func setPlaceHolder(placeholder:String){
            self.label.text = placeholder
        }

        override public func becomeFirstResponder() -> Bool {

            var flag:Bool = super.becomeFirstResponder()

            if flag {

                if self.floatingLabel! {

                    if !self.floating! || self.text!.isEmpty {
                        self.floatLabelToTop()
                        self.floating = true
                    }
                } else {
                    self.label.textColor = kDefaultActiveColor
                    self.label.layer.opacity = 0
                }
                self.showActiveBorder()
            }

            self.active=flag
            return flag
        }
        override public func resignFirstResponder() -> Bool {

            var flag:Bool = super.becomeFirstResponder()

            if flag {

                if self.floatingLabel! {

                    if self.floating! && self.text!.isEmpty {
                        self.animateLabelBack()
                        self.floating = false
                    }
                } else {
                    if self.text!.isEmpty {
                        self.label.layer.opacity = 1
                    }
                }
                self.label.textColor = kDefaultInactiveColor
                self.showInactiveBorder()
                self.validate()
            }
            self.active = flag
            return flag

        }

        override public func drawRect(rect: CGRect){
            super.drawRect(rect)

            var borderColor = self.hasError! ? kDefaultErrorColor : kDefaultInactiveColor

            var textRect = self.textRectForBounds(rect)
            var context = UIGraphicsGetCurrentContext()
            var borderlines : [CGPoint] = [CGPointMake(0, CGRectGetHeight(textRect) - 1),
                CGPointMake(CGRectGetWidth(textRect), CGRectGetHeight(textRect) - 1)]

            if  self.enabled  {

                CGContextBeginPath(context);
                CGContextAddLines(context, borderlines, 2);
                CGContextSetLineWidth(context, 1.0);
                CGContextSetStrokeColorWithColor(context, borderColor.CGColor);
                CGContextStrokePath(context);

            } else {

                CGContextBeginPath(context);
                CGContextAddLines(context, borderlines, 2);
                CGContextSetLineWidth(context, 1.0);
                var  dashPattern : [CGFloat]  = [2, 4]
                CGContextSetLineDash(context, 0, dashPattern, 2);
                CGContextSetStrokeColorWithColor(context, borderColor.CGColor);
                CGContextStrokePath(context);

            }
        }

        func textDidChange(notif: NSNotification){
            self.validate()
        }

        func floatLabelToTop() {

            CATransaction.begin()
            CATransaction.setCompletionBlock { () -> Void in
                self.label.textColor = self.kDefaultActiveColor
            }

            var anim2 = CABasicAnimation(keyPath: "transform")
            var fromTransform = CATransform3DMakeScale(CGFloat(1.0), CGFloat(1.0), CGFloat(1))
            var toTransform = CATransform3DMakeScale(CGFloat(0.5), CGFloat(0.5), CGFloat(1))
            toTransform = CATransform3DTranslate(toTransform, -CGRectGetWidth(self.label.frame)/2, -CGRectGetHeight(self.label.frame), 0)
            anim2.fromValue = NSValue(CATransform3D: fromTransform)
            anim2.toValue = NSValue(CATransform3D: toTransform)
            anim2.timingFunction = CAMediaTimingFunction(name: kCAMediaTimingFunctionEaseOut)
            var animGroup = CAAnimationGroup()
            animGroup.animations = [anim2]
            animGroup.duration = 0.3
            animGroup.fillMode = kCAFillModeForwards;
            animGroup.removedOnCompletion = false;
            self.label.layer.addAnimation(animGroup, forKey: "_floatingLabel")
            self.clipsToBounds = false
            CATransaction.commit()
        }
        func showActiveBorder() {

            self.activeBorder.layer.transform = CATransform3DMakeScale(CGFloat(0.01), CGFloat(1.0), 1)
            self.activeBorder.layer.opacity = 1
            CATransaction.begin()
            self.activeBorder.layer.transform = CATransform3DMakeScale(CGFloat(0.01), CGFloat(1.0), 1)
            var anim2 = CABasicAnimation(keyPath: "transform")
            var fromTransform = CATransform3DMakeScale(CGFloat(0.01), CGFloat(1.0), 1)
            var toTransform = CATransform3DMakeScale(CGFloat(1.0), CGFloat(1.0), 1)
            anim2.fromValue = NSValue(CATransform3D: fromTransform)
            anim2.toValue = NSValue(CATransform3D: toTransform)
            anim2.timingFunction = CAMediaTimingFunction(name: kCAMediaTimingFunctionEaseOut)
            anim2.fillMode = kCAFillModeForwards
            anim2.removedOnCompletion = false
            self.activeBorder.layer.addAnimation(anim2, forKey: "_activeBorder")
            CATransaction.commit()
        }

        func animateLabelBack() {
            CATransaction.begin()
            CATransaction.setCompletionBlock { () -> Void in
                self.label.textColor = self.kDefaultInactiveColor
            }

            var anim2 = CABasicAnimation(keyPath: "transform")
            var fromTransform = CATransform3DMakeScale(0.5, 0.5, 1)
            fromTransform = CATransform3DTranslate(fromTransform, -CGRectGetWidth(self.label.frame)/2, -CGRectGetHeight(self.label.frame), 0);
            var toTransform = CATransform3DMakeScale(1.0, 1.0, 1)
            anim2.fromValue = NSValue(CATransform3D: fromTransform)
            anim2.toValue = NSValue(CATransform3D: toTransform)
            anim2.timingFunction = CAMediaTimingFunction(name: kCAMediaTimingFunctionEaseOut)

            var animGroup = CAAnimationGroup()
            animGroup.animations = [anim2]
            animGroup.duration = 0.3
            animGroup.fillMode = kCAFillModeForwards;
            animGroup.removedOnCompletion = false;

            self.label.layer.addAnimation(animGroup, forKey: "_animateLabelBack")
            CATransaction.commit()
        }
        func showInactiveBorder() {

            CATransaction.begin()
            CATransaction.setCompletionBlock { () -> Void in
                self.activeBorder.layer.opacity = 0
            }
            var anim2 = CABasicAnimation(keyPath: "transform")
            var fromTransform = CATransform3DMakeScale(1.0, 1.0, 1)
            var toTransform = CATransform3DMakeScale(0.01, 1.0, 1)
            anim2.fromValue = NSValue(CATransform3D: fromTransform)
            anim2.toValue = NSValue(CATransform3D: toTransform)
            anim2.timingFunction = CAMediaTimingFunction(name: kCAMediaTimingFunctionEaseOut)
            anim2.fillMode = kCAFillModeForwards
            anim2.removedOnCompletion = false
            self.activeBorder.layer.addAnimation(anim2, forKey: "_activeBorder")
            CATransaction.commit()
        }

        func performValidation(isValid:Bool,message:String){
            if !isValid {
                self.hasError = true
                self.errorMessage = message
                self.labelTextColor = kDefaultErrorColor
                self.activeBorder.backgroundColor = kDefaultErrorColor
                self.setNeedsDisplay()
            } else {
                self.hasError = false
                self.errorMessage = nil
                self.labelTextColor = kDefaultActiveColor
                self.activeBorder.backgroundColor = kDefaultActiveColor
                self.setNeedsDisplay()
            }
        }

        func validate(){

            if self.validationType != nil {
                var message : String = ""

                if self.validationType! == .Email {

                    var isValid = self.emailValidationBlock(text: self.text, message: &message)

                    performValidation(isValid,message: message)

                } else {
                    var isValid = self.numberValidationBlock(text: self.text, message: &message)

                    performValidation(isValid,message: message)
                }
            }
        }


    }

    extension EGFloatingTextField {

    }

他的名字是

EGFloatingTextField

，您可以找到更多详细信息

用法：

let emailLabel = EGFloatingTextField(frame: CGRectMake(8, 64, CGRectGetWidth(self.view.bounds) - 16, 48))
emailLabel.floatingLabel = true
emailLabel.setPlaceHolder("Email")
emailLabel.validationType = .Email
emailLabel.keyboardType = .EmailAddress
self.view.addSubview(emailLabel)

另外，您需要导入

PureLayout

库，您可以找到完整的源代码以及如何导入它的说明

---

实现此功能时遇到问题-即使我在pod文件中写入了所需的行，也无法使用import PureLayout获得此类模块。我应该在单独的脚本中添加所有这些内容吗？当我这样做的时候，它不知道这里的EG文本字段是什么样子的：还有关于如何导入itOk的说明，我看了一遍，但有点模糊——当我在单独的文件中导入它时，我没有收到错误，只是当我在我的视图控制器文件中导入它时。我是否将上述代码放在一个单独的文件中？通常我对这些手动说明没有问题：它说运行pod安装，但我不知道这意味着什么-pod安装什么？我写pod安装Purelayout吗？关于如何在标签中设置缩放动画有什么想法吗？我试过CGAffineTransform，但它像上面答案的gif一样跳跃帧/不平滑。我远离键盘，我将发布EODI的简单解决方案，我认为这些就是你想要的效果（hoshi，我相信它被称为）。