ios WKWebView 注意事项和坑

1.内存泄漏

现象：WKWebView所在的ViewController不执行dealloc

原因：下面的代码引起

WKWebViewConfiguration * wkconfiguration = [[WKWebViewConfiguration alloc]init];
// userContentController 强引用了 self （控制器）
[wkconfiguration.userContentController addScriptMessageHandler:self name:@"JsBridge"];

如果没有执行对应的removeScriptMessageHandlerForName，就会造成内存泄漏。

解决办法:
方法1.新建一个类

WeakScriptMessageDelegate.h

#import <Foundation/Foundation.h>
#import <WebKit/WebKit.h>

@interface WeakScriptMessageDelegate : NSObject<WKScriptMessageHandler>

@property (nonatomic,weak)id<WKScriptMessageHandler> scriptDelegate;

- (instancetype)initWithDelegate:(id<WKScriptMessageHandler>)scriptDelegate;

@end


WeakScriptMessageDelegate.m

#import "WeakScriptMessageDelegate.h"


@implementation WeakScriptMessageDelegate

- (instancetype)initWithDelegate:(id<WKScriptMessageHandler>)scriptDelegate{
    self = [super init];
    if (self) {
        _scriptDelegate = scriptDelegate;
    }
    return self;
}

- (void)userContentController:(WKUserContentController *)userContentController didReceiveScriptMessage:(WKScriptMessage *)message{
    [self.scriptDelegate userContentController:userContentController didReceiveScriptMessage:message];
}

@end

然后对应改成：

WKWebViewConfiguration * wkconfiguration = [[WKWebViewConfiguration alloc]init];
[wkconfiguration.userContentController addScriptMessageHandler:[[WeakScriptMessageDelegate alloc] initWithDelegate:self] name:@"JsBridge"];

方法2：（不建议用这个）

- (void)viewWillDisappear:(BOOL)animated
{
    [super viewWillDisappear:animated];
    [self.webView.configuration.userContentController removeScriptMessageHandlerForName:@"JsBridge"];
    
}
//因为移除后跟js的交互就失效了，viewWillDisappear并不代表dealloc了

2.页面空白

现象： 有时候返回到上一个页面发现页面变空白了，或者从后台切会到前台后发现页面空白了

原因：我猜测是内存扛不住了
解决办法:（9.0及以后）

- (void)webViewWebContentProcessDidTerminate:(WKWebView *)webView{
    //reload你的URL
}
//注意这个是wkwebview.navigationDelegate的协议