IOS开发随笔

1,后台返回图片太大了.

用collectionView, 后台返回图片太大, 滑动就会有点卡 内存还会有点大
以下是我做的处理 -- 异步裁剪图片

-(void)setModel:(GoodsDetailModel *)model{
    _model = model;

//  [_wineImagev sd_setImageWithURL:BeURL(GetFullUrlStr(model.imgPath)) placeholderImage:[UIImage imageNamed:@"icon_loading_wine.png"]];
    
     SDWebImageManager* webManger = [SDWebImageManager sharedManager];
  
    [webManger downloadImageWithURL:BeURL(GetFullUrlStr(model.imgPath)) options:SDWebImageRetryFailed progress:nil completed:^(UIImage *image, NSError *error, SDImageCacheType cacheType, BOOL finished, NSURL *imageURL) {
            
            if (image.size.width > 300) {
                
                dispatch_async(dispatch_get_global_queue(0, 0), ^{
                    
                    CGFloat scale = image.size.width / 300;
                    UIImage*img = UIImageScaleToSize(image,CGSizeMake(300, image.size.height / scale));
                    
                    dispatch_async(dispatch_get_main_queue(), ^{
                        self.wineImagev.image = img;
                    });
                });
            }else{
                self.wineImagev.image = image;
            }
        }];

//修改图片尺寸
UIImage * UIImageScaleToSize(UIImage *img, CGSize size){

    UIGraphicsBeginImageContext(size);
   
    [img drawInRect:CGRectMake(0, 0, size.width, size.height)];
  
    UIImage* scaledImage = UIGraphicsGetImageFromCurrentImageContext();

    UIGraphicsEndImageContext();
 
    return scaledImage;
}

如果内存还是太大的话 可以这样设置SD

  [[SDImageCache sharedImageCache] setShouldCacheImagesInMemory:NO];
  [[SDImageCache sharedImageCache] setShouldDecompressImages:NO];
  [[SDWebImageDownloader sharedDownloader] setShouldDecompressImages:NO];

2, 用TTTAttributedLabel 给label中关键词加点击事件

屏幕快照 2016-09-08 17.49.57.png

 _attributeLabel = [[TTTAttributedLabel alloc]initWithFrame:CGRectMake(10, 50, SCREEN_SIZE.width - 20, 200)];
    _attributeLabel.numberOfLines = 0;
    _attributeLabel.backgroundColor = [UIColor groupTableViewBackgroundColor];
    _attributeLabel.delegate = self;
    
    NSMutableAttributedString* attStr = [[NSMutableAttributedString alloc]initWithString:@"多少年都未曾忘记2005年清晨哪位和我视频的女网友:夜未央。那海藻般的头发，白色的棉布内衣，如同安妮宝贝笔下那个，慵懒，干净，纯净的女子一般。当她对我微微一笑，我即刻头晕目眩，感觉生命仿佛被一道白光刺穿，涉世未深的我第一次感觉到了成熟女人的魅力，依依不舍的关掉视频后，我昏睡了整整10天 -- 杀马特强子"];
    
    NSString* keyStr1 = @"夜未央", * keyStr2 = @"安妮宝贝";
    
    NSRange range1 = [attStr.string rangeOfString:keyStr1];
    NSRange range2 = [attStr.string rangeOfString:keyStr2];
    
    //设置整体属性字符串
    [attStr addAttribute:NSFontAttributeName value:[UIFont boldSystemFontOfSize:17] range:NSMakeRange(0, attStr.length)];
    [attStr addAttribute:NSForegroundColorAttributeName value:[UIColor darkGrayColor] range:RangeAll(attStr)];
    
    NSMutableParagraphStyle* style = [[NSMutableParagraphStyle alloc]init];
    style.lineSpacing = 5;
    [attStr addAttribute:NSParagraphStyleAttributeName value:style range:RangeAll(attStr)];
    
    [_attributeLabel setText:attStr];
    
    //正常状态下的属性
    _attributeLabel.linkAttributes = @{
                                       (NSString *)kCTForegroundColorAttributeName: [UIColor orangeColor],
                                       (NSString *)kCTUnderlineStyleAttributeName: @(YES)
                                       };
    //点下去时的属性
    _attributeLabel.activeLinkAttributes = @{
                                             (NSString *)kCTForegroundColorAttributeName: [UIColor cyanColor]
                                             };
    //不活跃时的属性 比如弹出alert时
    _attributeLabel.inactiveLinkAttributes = _attributeLabel.linkAttributes;
    
    //添加点击事件 传入字典 在代理或block拿到
    TTTAttributedLabelLink* link1 = [_attributeLabel addLinkToTransitInformation:@{@"001":keyStr1} withRange:range1];
    
    [_attributeLabel addLinkToTransitInformation:@{@"002":keyStr2} withRange:range2];
    
    
    //可以使用点击事件block 或者 使用代理
    //    link1.linkTapBlock =  ^(TTTAttributedLabel *attributeLabel, TTTAttributedLabelLink *labeLink){
    //
    //        NSDictionary* dic = labeLink.result.components;
    //
    //        if (dic) {
    //
    //        }
    //    };
    
    [self.view addSubview:_attributeLabel];

#pragma mark - 点击事件代理
- (void)attributedLabel:(TTTAttributedLabel *)label
didSelectLinkWithTransitInformation:(NSDictionary *)components{

    if (components) {
        
        NSString* msg = [NSString stringWithFormat:@"点击了%@",[[components allValues] lastObject]];
        
        [self alertMessage:msg];
    }
}

注意:
cell 在重用的时候，之前设的 link 都没有清除

必须使用: self.attributedLabel.text = attributedString;

不要用: self.attributedLabel.attributedText = attributedString;

TTTAttributedLabel下载地址
https://github.com/TTTAttributedLabel/TTTAttributedLabel

3.用LDRefresh 实现防淘宝商品详情中查看宝贝图文详情方式tableview 与 webview 的切换 https://github.com/SNTD/LDRefresh

LDRefresh.gif

4,用UISegmentedControl 通过addChildViewController 控制两个控制器的切换

//首先用一个主控制器 管理两个子控制器

   self.fristVC = [[HomeMutableSaleVC alloc] init];
   self.secondVC = [[HomeMapController alloc] init];
    
    self.fristVC.view.frame = CGRectMake(0, CGRectGetMaxY(self.navigationView.frame), kScreenWidth, kScreenHeight - self.navigationView.height);
    self.secondVC.view.frame = CGRectMake(kScreenWidth, CGRectGetMaxY(self.navigationView.frame), kScreenWidth, kScreenHeight - self.navigationView.height);
    
    //  默认,第一个视图
    [self.view addSubview:self.fristVC.view];
    [self.view addSubview:self.secondVC.view];
    [self addChildViewController:self.fristVC];

-(void)swichTitleAction:(UISegmentedControl*)segmen{

 if ((self.currectVC == self.fristVC && segmen.selectedSegmentIndex ==0) || (self.currectVC == self.secondVC && segmen.selectedSegmentIndex == 1)) { 
      return;
 }

//--------ChildViewcontroller 间的切换--------------//
UIViewController* oldController = self.currectVC;
UIViewController*  newController = segmen.selectedSegmentIndex == 0? self.fristVC:self.secondVC;
 newController.view.frame = oldController.view.frame;
 [self addChildViewController:newController];

 [self transitionFromViewController:oldController toViewController:newController duration:0.1 options:UIViewAnimationOptionTransitionCrossDissolve animations:nil completion:^(BOOL finished) {
        
        if (finished) {
            
            [newController didMoveToParentViewController:self];
            [oldController willMoveToParentViewController:nil];
            [oldController removeFromParentViewController];
            self.currectVC = newController;
        }else{
            
            self.currectVC = oldController;
        }
    }];
}

5, 快速实现图片和View的模糊效果 FXBlurView -- https://github.com/nicklockwood/FXBlurView

6, 很多时候使用UIWebView 会导致内存增加很大. 这个时候建议使用WKWebView,WKWebView 内存占用非常小... WKWebView是iOS8 以后使用的, 然而Xcode8 都不支持iOS7了 还有什么理由 不用WKWebView代替UIWebView呢?

WKWebView的使用:

(1), 添加依赖库: WebKit.framework

(2), 导入 #import <WebKit/WebKit.h>

(3),创建webview 跟之前的UIWebView 类似的

-(WKWebView *)webView{
    if (!_webView) {
        _webView = [[WKWebView alloc]initWithFrame:];
        _webView.navigationDelegate = self;
        _webView.scrollView.scrollEnabled = YES;
     
         [self.view addSubview:_webView];

        NSURLRequest* request = [NSURLRequest requestWithURL:[NSURL URLWithString:urlStr] cachePolicy:NSURLRequestUseProtocolCachePolicy timeoutInterval:30];
        [_webView loadRequest:request];
    }
    return _webView;
}

navigationDelegate 的代理方法

// 开始加载
- (void)webView:(WKWebView *)webView didStartProvisionalNavigation:(WKNavigation *)navigation;
// 加载完成
- (void)webView:(WKWebView *)webView didFinishNavigation:(WKNavigation *)navigation;
// 加载失败
- (void)webView:(WKWebView *)webView didFailProvisionalNavigation:(WKNavigation *)navigation;

更多WKWebView请点击:http://nshipster.cn/wkwebkit/ http://www.jianshu.com/p/403853b63537

7, 解决webview 中的文字乱码 ! !

 dispatch_async(dispatch_get_global_queue(0, 0), ^{
            
        NSString * htmlStr = [[NSString alloc]initWithContentsOfURL:[NSURL URLWithString:urlStr] encoding:NSUTF8StringEncoding error:nil];
      
          [_webView loadHTMLString:htmlStr baseURL:[NSURL URLWithString:urlStr]]; 
 });

代替下面这种写法:

    NSURLRequest* request = [NSURLRequest requestWithURL:[NSURL URLWithString:urlStr] cachePolicy:NSURLRequestUseProtocolCachePolicy timeoutInterval:30];
   [_webView loadRequest:request];