我是 ios 编程的新手。我试图在 stackoverflow 上搜索另一个示例和更多问题，但这不是我的目标。我想在 UIPageControl 的索引 0 处设置一个点图像，类似于 iPhone 搜索主屏幕。有什么办法吗？请用一些代码或其他有用的链接解释一下。
提前致谢
【问题讨论】：
UIView 动画。
我创建了一个自定义页面控制器，它应该以几乎相同的方式运行，而无需侵入 UIPageControl 的内部或为一个小部件提供整个库。
只需在情节提要中放置一个空的 UIStackView 并将其自定义类设为下面的此类，然后像普通 UIPageControl 一样使用numberOfPages 和currentPage。在 UIStackView 上设置间距以更改视图之间的间距。
斯威夫特 4.2
/**
If adding via storyboard, you should not need to set a width and height constraint for this view,
just set a placeholder for each so autolayout doesnt complain and this view will size itself once its populated with pages at runtime
*/
class PageControl: UIStackView {
@IBInspectable var currentPageImage: UIImage = UIImage(named: "whiteCircleFilled")!
@IBInspectable var pageImage: UIImage = UIImage(named: "whiteCircleOutlined")!
/**
Sets how many page indicators will show
*/
var numberOfPages = 3 {
didSet {
layoutIndicators()
}
}
/**
Sets which page indicator will be highlighted with the **currentPageImage**
*/
var currentPage = 0 {
didSet {
setCurrentPageIndicator()
}
}
override func awakeFromNib() {
super.awakeFromNib()
axis = .horizontal
distribution = .equalSpacing
alignment = .center
layoutIndicators()
}
private func layoutIndicators() {
for i in 0..<numberOfPages {
let imageView: UIImageView
if i < arrangedSubviews.count {
imageView = arrangedSubviews[i] as! UIImageView // reuse subview if possible
} else {
imageView = UIImageView()
addArrangedSubview(imageView)
}
if i == currentPage {
imageView.image = currentPageImage
} else {
imageView.image = pageImage
}
}
// remove excess subviews if any
let subviewCount = arrangedSubviews.count
if numberOfPages < subviewCount {
for _ in numberOfPages..<subviewCount {
arrangedSubviews.last?.removeFromSuperview()
}
}
}
private func setCurrentPageIndicator() {
for i in 0..<arrangedSubviews.count {
let imageView = arrangedSubviews[i] as! UIImageView
if i == currentPage {
imageView.image = currentPageImage
} else {
imageView.image = pageImage
}
}
}
}
为我的目的工作，但我不做任何保证
【讨论】：
试试这个链接：-
用 GrayPageControl 回答：- Is there a way to change page indicator dots color
真的很好，很可靠。我也用过这段代码。
你可能需要做更多的自定义
-(void) updateDots
{
for (int i = 0; i < [self.subviews count]; i++)
{
UIImageView* dot = [self.subviews objectAtIndex:i];
if (i == self.currentPage) {
if(i==0) {
dot.image = [UIImage imageNamed:@"activesearch.png"];
} else {
dot.image = activeImage;
}
} else {
if(i==0) {
dot.image = [UIImage imageNamed:@"inactivesearch.png"];
} else {
dot.image = inactiveImage;
}
}
}
}
【讨论】：
我已经找到了解决这个问题的方法。我知道这不是办法，但它会在 iOS 8 上市之前一直有效。
崩溃原因：
在 iOS 7 [self.subViews objectAtIndex: i] 返回 UIView 而不是 UIImageView 并且 setImage 不是 UIView 的属性并且应用程序崩溃。我使用以下代码解决了我的问题。
检查子视图是 UIView(iOS7) 还是 UIImageView(iOS6 或更早版本)。如果它是 UIView，我将在该视图上添加 UIImageView 作为子视图，瞧它的工作，而不是崩溃..！！
-(void) updateDots
{
for (int i = 0; i < [self.subviews count]; i++)
{
UIImageView * dot = [self imageViewForSubview: [self.subviews objectAtIndex: i]];
if (i == self.currentPage) dot.image = activeImage;
else dot.image = inactiveImage;
}
}
- (UIImageView *) imageViewForSubview: (UIView *) view
{
UIImageView * dot = nil;
if ([view isKindOfClass: [UIView class]])
{
for (UIView* subview in view.subviews)
{
if ([subview isKindOfClass:[UIImageView class]])
{
dot = (UIImageView *)subview;
break;
}
}
if (dot == nil)
{
dot = [[UIImageView alloc] initWithFrame:CGRectMake(0.0f, 0.0f, view.frame.size.width, view.frame.size.height)];
[view addSubview:dot];
}
}
else
{
dot = (UIImageView *) view;
}
return dot;
}
另外，要清除已经存在的图像，请将现有指示器的色调设置为透明：
- (void)awakeFromNib
{
self.pageIndicatorTintColor = [UIColor clearColor];
self.currentPageIndicatorTintColor = [UIColor clearColor];
}
希望这将解决您的 iOS 7 问题。
愉快的编码
【讨论】：
Swift 3 代码的最佳编译，用位置标记替换UIPageControl 的第一个图标：
import UIKit
class LocationPageControl: UIPageControl {
let locationArrow: UIImage = UIImage(named: "locationArrow")!
let pageCircle: UIImage = UIImage(named: "pageCircle")!
override var numberOfPages: Int {
didSet {
updateDots()
}
}
override var currentPage: Int {
didSet {
updateDots()
}
}
override func awakeFromNib() {
super.awakeFromNib()
self.pageIndicatorTintColor = UIColor.clear
self.currentPageIndicatorTintColor = UIColor.clear
self.clipsToBounds = false
}
func updateDots() {
var i = 0
for view in self.subviews {
var imageView = self.imageView(forSubview: view)
if imageView == nil {
if i == 0 {
imageView = UIImageView(image: locationArrow)
} else {
imageView = UIImageView(image: pageCircle)
}
imageView!.center = view.center
view.addSubview(imageView!)
view.clipsToBounds = false
}
if i == self.currentPage {
imageView!.alpha = 1.0
} else {
imageView!.alpha = 0.5
}
i += 1
}
}
fileprivate func imageView(forSubview view: UIView) -> UIImageView? {
var dot: UIImageView?
if let dotImageView = view as? UIImageView {
dot = dotImageView
} else {
for foundView in view.subviews {
if let imageView = foundView as? UIImageView {
dot = imageView
break
}
}
}
return dot
}
}
附加图片：
【讨论】：
只需将 UIPageControl 页面指示器颜色更改为图案 Image self.pageControl.currentPageIndicatorTintColor = [UIColor colorWithPatternImage:[UIImage imageNamed:@"circle"]];
【讨论】：
Swift 3.0 的更新......你知道你是否可以接受声明的风险：“修改现有控件的子视图是脆弱的”。
import UIKit
class CustomImagePageControl: UIPageControl {
let activeImage:UIImage = UIImage(named: "SelectedPage")!
let inactiveImage:UIImage = UIImage(named: "UnselectedPage")!
override func awakeFromNib() {
super.awakeFromNib()
self.pageIndicatorTintColor = UIColor.clear
self.currentPageIndicatorTintColor = UIColor.clear
self.clipsToBounds = false
}
func updateDots() {
var i = 0
for view in self.subviews {
if let imageView = self.imageForSubview(view) {
if i == self.currentPage {
imageView.image = self.activeImage
} else {
imageView.image = self.inactiveImage
}
i = i + 1
} else {
var dotImage = self.inactiveImage
if i == self.currentPage {
dotImage = self.activeImage
}
view.clipsToBounds = false
view.addSubview(UIImageView(image:dotImage))
i = i + 1
}
}
}
fileprivate func imageForSubview(_ view:UIView) -> UIImageView? {
var dot:UIImageView?
if let dotImageView = view as? UIImageView {
dot = dotImageView
} else {
for foundView in view.subviews {
if let imageView = foundView as? UIImageView {
dot = imageView
break
}
}
}
return dot
}
}
【讨论】：
numberOfPages 和currentPage 调用updateDots() 会好很多观察者：stackoverflow.com/a/41136917/865475
updateDots？我在viewDidLoad 内调用它，但不起作用。
你只需要这样做：
((UIImageView *)[[yourPageControl subviews] objectAtIndex:0]).image=[UIImage imageNamed:@"search.png"];
【讨论】：
我认为为此您需要自定义整个UIPageControl。请在下面的链接中找到更多信息
【讨论】：
来自 iProgrammer 的回答
如果您想隐藏原始点
- (UIImageView *)imageViewForSubview:(UIView *)view {
UIImageView * dot = nil;
[view setBackgroundColor:[UIColor clearColor]]; << add this line
【讨论】：
按照之前的答案，我想出了下面的解决方案。 请记住，我必须在控制器中添加调用 updateDots() 的 valueChanged 侦听器来处理在 UIPageControl 上进行的点击
import UIKit
class PageControl: UIPageControl {
private struct Constants {
static let activeColor: UIColor = .white
static let inactiveColor: UIColor = .black
static let locationImage: UIImage = UIImage(named: "Location")!
}
// Update dots when currentPage changes
override var currentPage: Int {
didSet {
updateDots()
}
}
override func awakeFromNib() {
super.awakeFromNib()
self.pageIndicatorTintColor = .clear
self.currentPageIndicatorTintColor = .clear
}
func updateDots() {
for (index, view) in self.subviews.enumerated() {
// Layers will be redrawn, remove old.
view.layer.sublayers?.removeAll()
if index == 0 {
drawImage(view: view)
} else {
drawDot(index: index, view: view)
}
}
}
private func drawDot(index: Int, view: UIView) {
let dotLayer = CAShapeLayer()
dotLayer.path = UIBezierPath(ovalIn: view.bounds).cgPath
dotLayer.fillColor = getColor(index: index)
view.layer.addSublayer(dotLayer)
}
private func drawImage(view: UIView) {
let height = view.bounds.height * 2
let width = view.bounds.width * 2
let topMargin: CGFloat = -3.5
let maskLayer = CALayer()
maskLayer.frame = CGRect(x: 0, y: 0, width: width, height: height)
maskLayer.contents = Constants.locationImage.cgImage
maskLayer.contentsGravity = .resizeAspect
let imageLayer = CALayer()
imageLayer.frame = CGRect(x:0, y: topMargin, width: width, height: height)
imageLayer.mask = maskLayer
imageLayer.backgroundColor = getColor()
view.backgroundColor = .clear // Otherwise black background
view.layer.addSublayer(imageLayer)
}
private func getColor(index: Int? = 0) -> CGColor {
return currentPage == index ? Constants.activeColor.cgColor : Constants.inactiveColor.cgColor
}
}
【讨论】：
从 iOS 14 开始，您可以使用以下方法获取和设置指示器图像：
@available(iOS 14.0, *)
open func indicatorImage(forPage page: Int) -> UIImage?
@available(iOS 14.0, *)
open func setIndicatorImage(_ image: UIImage?, forPage page: Int)
【讨论】：