一、UIWebview的发现
问题发现：当UIWebview王深层次点击的时候，返回时需要webView执行goBack方法一级一级返回，这样看到的webView只是在该界面执行刷新，并看不到类似iOS系统那样的侧滑返回上一级。
实现思想：我们可以从第一级开始对每一级webView加载的内容，截取屏幕的图片并保存到数组中，然后给webView添加pan手势,判断手势侧滑的时候，添加UIImageView显示视频里面截图的内容，同时调整webView的x值和imageView的x值，当侧滑完全返回时，移除imageView,webView并重新加载新的链接，即可实现侧滑返回效果。
二、实现代码如下
1、DLPanableWebView.h代码实现
#import <UIKit/UIKit.h>
@class DLPanableWebView;
@protocol DLPanableWebViewDelegate <NSObject>
// 0 成功 1 完成 2 失败
- (void)webViewLoadState:(NSInteger)state;
@optional
- (void)panableWebView:(DLPanableWebView *)webView panPopGesture:(UIPanGestureRecognizer *)pan;
@end
@interface DLPanableWebView : UIWebView
@property(nonatomic, weak) id <DLPanableWebViewDelegate> panDelegate;
@property(nonatomic, assign) BOOL enablePanGesture;
- (void)goBack;
@end
2、DLPanableWebView.m代码实现
#import "DLPanableWebView.h"
@interface DLPanableWebView()<UIWebViewDelegate>
@property (nonatomic, strong) UIGestureRecognizer* popGesture;
@property (nonatomic, weak) id <UIWebViewDelegate> originDelegate;
@property (nonatomic, strong)UIImageView *historyView;
@property (nonatomic, strong) NSMutableArray *historyStack;
@property (nonatomic, assign) CGFloat panStartX;
@end
@implementation DLPanableWebView
+ (UIImage *)screenshotOfView:(UIView *)view {
UIGraphicsBeginImageContextWithOptions(view.frame.size, YES, 0.0);
if ([view respondsToSelector:@selector(drawViewHierarchyInRect:afterScreenUpdates:)]) {
[view drawViewHierarchyInRect:view.bounds afterScreenUpdates:YES];
}
else{
[view.layer renderInContext:UIGraphicsGetCurrentContext()];
}
UIImage *image = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
return image;
}
+ (void)addShadowToView:(UIView *)view{
CALayer *layer = view.layer;
UIBezierPath *path = [UIBezierPath bezierPathWithRect:layer.bounds];
layer.shadowPath = path.CGPath;
layer.shadowColor = [UIColor blackColor].CGColor;
layer.shadowOffset = CGSizeZero;
layer.shadowOpacity = 0.4f;
layer.shadowRadius = 8.0f;
}
- (void)setDelegate:(id<UIWebViewDelegate>)delegate{
self.originDelegate = delegate;
}
- (id<UIWebViewDelegate>)delegate{
return self.originDelegate;
}
- (void)goBack{
[super goBack];
[self.historyStack removeLastObject];
}
- (void)setEnablePanGesture:(BOOL)enablePanGesture{
self.popGesture.enabled = enablePanGesture;
}
- (BOOL)enablePanGesture{
return self.popGesture.enabled;
}
- (NSMutableArray *)historyStack {
if (!_historyStack) {
_historyStack = [NSMutableArray array];
}
return _historyStack;
}
- (UIImageView *)historyView{
if (!_historyView) {
if (self.superview) {
_historyView = [[UIImageView alloc] initWithFrame:self.bounds];
[self.superview insertSubview:_historyView belowSubview:self];
}
}
return _historyView;
}
- (id)init{
if (self = [super init]) {
[self commonInit];
}
return self;
}
- (id)initWithCoder:(NSCoder *)aDecoder{
if (self = [super initWithCoder:aDecoder]) {
[self commonInit];
}
return self;
}
- (id)initWithFrame:(CGRect)frame{
if (self = [super initWithFrame:frame]) {
[self commonInit];
}
return self;
}
- (void)commonInit{
self.popGesture = [[UIPanGestureRecognizer alloc] initWithTarget:self action:@selector(panGesture:)];
[self addGestureRecognizer:self.popGesture];
[super setDelegate:self];
[DLPanableWebView addShadowToView:self];
}
- (void)dealloc {
if (self.historyView) {
[self.historyView removeFromSuperview];
self.historyView = nil;
}
}
- (void)layoutSubviews {
[super layoutSubviews];
self.historyView.frame = self.bounds;
}
#pragma mark === gesture===
- (void)panGesture:(UIPanGestureRecognizer *)sender{
if (![self canGoBack] || self.historyStack.count == 0) {
if (self.panDelegate && [self.panDelegate respondsToSelector:@selector(panableWebView:panPopGesture:)]) {
[self.panDelegate panableWebView:self panPopGesture:sender];
}
return;
}
CGPoint point = [sender translationInView:self];
if (sender.state == UIGestureRecognizerStateBegan) {
_panStartX = point.x;
}
else if (sender.state == UIGestureRecognizerStateChanged){
CGFloat deltaX = point.x - _panStartX;
if (deltaX > 0) {
if ([self canGoBack]) {
assert(self.historyStack.count > 0);
self.historyView.image = [self.historyStack.lastObject objectForKey:@"preview"];
self.x = deltaX;
self.historyView.x = -self.width / 2.0f + deltaX / 2.0f;
}
}
}
else if (sender.state == UIGestureRecognizerStateEnded){
CGFloat deltaX = point.x - _panStartX;
CGFloat duration = .5f;
if ([self canGoBack]) {
if (deltaX > self.width / 4.0f) {
[UIView animateWithDuration:(1.0f - deltaX / self.width) * duration animations:^{
self.x = self.width;
self.historyView.x = 0;
[self goBack];
} completion:^(BOOL finished) {
self.x = 0;
[self.historyView removeFromSuperview];
self.historyView = nil;
}];
}
else{
[UIView animateWithDuration:(deltaX/self.bounds.size.width)*duration animations:^{
CGRect rc = self.frame;
rc.origin.x = 0;
self.frame = rc;
rc.origin.x = -self.bounds.size.width/2.0f;
self.historyView.frame = rc;
} completion:^(BOOL finished) {
}];
}
}
}
}
#pragma mark ===uiwebview===
- (BOOL)webView:(UIWebView *)webView shouldStartLoadWithRequest:(NSURLRequest *)request navigationType:(UIWebViewNavigationType)navigationType{
BOOL ret = YES;
if (self.originDelegate && [self.originDelegate respondsToSelector:@selector(webView:shouldStartLoadWithRequest:navigationType:)]) {
ret = [self.originDelegate webView:webView shouldStartLoadWithRequest:request navigationType:navigationType];
}
BOOL isFragmentJump = NO;
if (request.URL.fragment) {
NSString *nonFragmentURL = [request.URL.absoluteString stringByReplacingOccurrencesOfString:[@"#" stringByAppendingString:request.URL.fragment] withString:@""];
if (webView.request.URL.absoluteString) {
NSString *preNonFragmentURL;
if (webView.request.URL.fragment) {
preNonFragmentURL = [webView.request.URL.absoluteString stringByReplacingOccurrencesOfString:[@"#" stringByAppendingString:webView.request.URL.fragment] withString:@""];
}
else{
preNonFragmentURL = webView.request.URL.absoluteString;
}
isFragmentJump = [nonFragmentURL isEqualToString:preNonFragmentURL];
}
}
BOOL isTopLevelNavigation = [request.mainDocumentURL isEqual:request.URL];
BOOL isHTTPOrFile = [request.URL.scheme isEqualToString:@"http"] || [request.URL.scheme isEqualToString:@"https"] || [request.URL.scheme isEqualToString:@"file"];
if (ret && !isFragmentJump && isHTTPOrFile && isTopLevelNavigation) {
if ((navigationType == UIWebViewNavigationTypeLinkClicked || navigationType == UIWebViewNavigationTypeOther) && [[webView.request.URL description] length]) {
if (![[self.historyStack.lastObject objectForKey:@"url"] isEqualToString:[self.request.URL description]]) {
UIImage *curPreview = [DLPanableWebView screenshotOfView:self];
[self.historyStack addObject:@{@"preview":curPreview, @"url":[self.request.URL description]}];
}
}
}
// 点击自带返回，移除一个
if (navigationType == UIWebViewNavigationTypeBackForward) {
[self.historyStack removeLastObject];
}
NSLog(@"数组个数 ===> %zd",self.historyStack.count);
return ret;
}
- (void)webViewDidStartLoad:(UIWebView *)webView {
[UIApplication sharedApplication].networkActivityIndicatorVisible = YES;
if (self.originDelegate && [self.originDelegate respondsToSelector:@selector(webViewDidStartLoad:)]) {
[self.originDelegate webViewDidStartLoad:webView];
}
if ([self.panDelegate respondsToSelector:@selector(webViewLoadState:)]) {
[self.panDelegate webViewLoadState:0];
}
}
- (void)webViewDidFinishLoad:(UIWebView *)webView {
[UIApplication sharedApplication].networkActivityIndicatorVisible = NO;
if (self.originDelegate && [self.originDelegate respondsToSelector:@selector(webViewDidFinishLoad:)]) {
[self.originDelegate webViewDidFinishLoad:webView];
}
if ([self.panDelegate respondsToSelector:@selector(webViewLoadState:)]) {
[self.panDelegate webViewLoadState:1];
}
}
- (void)webView:(UIWebView *)webView didFailLoadWithError:(NSError *)error {
[UIApplication sharedApplication].networkActivityIndicatorVisible = NO;
if (self.originDelegate && [self.originDelegate respondsToSelector:@selector(webView:didFailLoadWithError:)]) {
[self.originDelegate webView:webView didFailLoadWithError:error];
}
if ([self.panDelegate respondsToSelector:@selector(webViewLoadState:)]) {
[self.panDelegate webViewLoadState:2];
}
}
@end