iOS7 UIWebview加载进度条实现

不同于WKWebview，wk是有自己的加载进度值的，我们可以直接通过kvo检测到，并显示到进度条内。

但如果我们为了适配ios7，只能使用UIWebview了，这里的加载进度，就比较尴尬了

所以我们的实现方式就是：模拟进度-俗称假进度。

实现原理：

自定义一个UIView的进度条，添加到Nav下方，给予两个方法：

1、startLoadingAnimation  开始加载

2、endLoadingAnimation  结束加载

开始加载，先动画模拟一个0.4s的加载，加载宽度为0.6倍屏幕宽度，动画结束，再0.4s实现，总共0.8倍的屏幕宽度。

结束动画，动画模拟1.0倍数的屏幕宽度，实现全部加载完成，并最后隐藏掉进度条。

代码：

.h文件

#import <UIKit/UIKit.h>

@interface WebviewProgressLine : UIView

//进度条颜色
@property (nonatomic,strong) UIColor  *lineColor;

//开始加载
-(void)startLoadingAnimation;

//结束加载
-(void)endLoadingAnimation;

@end

.m文件

#import "WebviewProgressLine.h"

@implementation WebviewProgressLine

-(instancetype)initWithFrame:(CGRect)frame{
    self = [super initWithFrame:frame];
    if (self) {
        self.hidden = YES;
        self.backgroundColor = [UIColor whiteColor];
    }
    return self;
}

-(void)setLineColor:(UIColor *)lineColor{
    _lineColor = lineColor;
    self.backgroundColor = lineColor;
}

-(void)startLoadingAnimation{
    self.hidden = NO;
    self.width = 0.0;
    
    __weak UIView *weakSelf = self;
    [UIView animateWithDuration:0.4 animations:^{
        weakSelf.width = KScreenWidth * 0.6;
    } completion:^(BOOL finished) {
        [UIView animateWithDuration:0.4 animations:^{
            weakSelf.width = KScreenWidth * 0.8;
        }];
    }];
    
    
}

-(void)endLoadingAnimation{
    __weak UIView *weakSelf = self;
    [UIView animateWithDuration:0.2 animations:^{
        weakSelf.width = KScreenWidth;
    } completion:^(BOOL finished) {
        weakSelf.hidden = YES;
    }];
}

@end

webview页面使用：

#import "webviewViewController.h"
#import "WebviewProgressLine.h"

@interface webviewViewController ()<UIWebViewDelegate>
@property (nonatomic,strong) UIWebView  *webview;
@property (nonatomic,strong) WebviewProgressLine  *progressLine;

@end

@implementation webviewViewController

- (void)viewDidLoad {
    [super viewDidLoad];
    self.view.backgroundColor = [UIColor whiteColor];
    
    self.webview = [[UIWebView alloc] initWithFrame:self.view.frame];
    self.webview.delegate = self;
    [self.view addSubview:self.webview];
    
    self.progressLine = [[WebviewProgressLine alloc] initWithFrame:CGRectMake(0, 64, KScreenWidth, 3)];
    self.progressLine.lineColor = [UIColor redColor];
    [self.view addSubview:self.progressLine];
    
    
    NSURL *url = [NSURL URLWithString:@"https://www.baidu.com"];
    [self.webview loadRequest:[NSURLRequest requestWithURL:url]];
    
}

-(void)webViewDidStartLoad:(UIWebView *)webView{
    [self.progressLine startLoadingAnimation];
}

-(void)webViewDidFinishLoad:(UIWebView *)webView{
    [self.progressLine endLoadingAnimation];
}

-(void)webView:(UIWebView *)webView didFailLoadWithError:(NSError *)error{
    [self.progressLine endLoadingAnimation];
}

由于内容比较简单，就不放Demo了，直接贴代码，大家可以试一下～