项目一（电影APP）——iOS学习连载26

1. 删除系统的tabbarItem

NSArray *array = self.tabBar.subviews;

//注意：UITabBarButton是一个私有的API，没有公开出来

//遍历tabbar中所有的子视图，并且移除tabbarItem

for (UIView *view in array) {

    Class cls = NSClassFromString(@"UITabBarButton");

    if ([view isKindOfClass: cls]) {

     //移除tabbar上的按钮

     [view removeFromSuperview];

     }

2. 动画修改选择视图的坐标

  [UIView animateWithDuration:0.3

                     animations:^{

                   _selectedImgView.center = item.center;

                     }];

3. 第一次添加到控制器视图上的子视图如果是ScrollView的对象（包含ScrollView子类的对象）,则视图的内容偏移量会根据是否有导航栏和标签栏进行扩充

4. 配置翻转动画(此方法与下面方法比较需要去求得翻转图片的下标)

        [UIView transitionWithView:imgView

                          duration:0.5

                           options:UIViewAnimationOptionTransitionFlipFromLeft
                        animations:^{
                            [self.view exchangeSubviewAtIndex:index1 withSubviewAtIndex:index2];
                        }

                        completion:nil];

5.翻转forView的两个子视图（forView：需要被翻转视图的父视图；flag：是否从左往右翻转）

//翻转视图

[self flipView:self.view left:btn1.hidden];

- (void)flipView:(UIView *)forView left:(BOOL)flag
{
    UIViewAnimationOptions flip;
    if(flag)

    {

      flip = UIViewAnimationOptionTransitionFlipFromLeft;

    }
    else

    {

     flip = UIViewAnimationOptionTransitionFlipFromRight;

    }
   
    //翻转
    [UIView transitionWithView:forView duration:0.5 options:flip animations:^{
       
    } completion:nil];

}

6.在iOS5.0之前解析json数据 ——> 使用第三方json解析工具: jsonKit/TouchJson/SBJson

  iOS5.0之后 ——> 使用NSJSONSerialization解析

7. //找到json数据路径

NSString *filePath = [[NSBundle mainBundle] pathForResource:us_box ofType:@"json"];

//从文件路径中获取数据

NSData *data = [NSData dataWithContentsOfFile:filePath];

//解析json----》转换成NSDictionary或者是NSArray

NSError *error = nil;

NSDictionary *jsonDic = [NSJSONSerialization JSONObjectWithData:data options:NSJSONReadingMutableContainers error:&error];

8. //拿到图片地址

NSString *urlStr = [self.movie.images objectForKey:@"medium"];

//构建URL方法一

NSURL *imgurl = [NSURL URLWithString:urlStr];

[_imgView sd_setImageWithURL:imgurl];

//构建URL方法二

NSURL *imgurl = [NSURL URLWithString:urlStr];

NSData *data = [NSData dataWithContentsOfURL:imgurl];

self.imageView.image = [UIImage imageWithData:data];

9. 当视图修改了transform后，坐标会变，需要重新恢复坐标

     CGPointMake(0, 0)与CGPointZero等效

10.只要改变数据源，就要刷新tableView

11. 隐藏状态栏

- (BOOL)prefersStatusBarHidden
{
    return self.navigationController.navigationBarHidden;
}

- (UIStatusBarAnimation)preferredStatusBarUpdateAnimation
{
    return UIStatusBarAnimationFade;

}

12. view =  layer + 事件接收

13. 设置边框宽度

  userImage.layer.borderWidth = 1;

 //设置边框颜色

  userImage.layer.borderColor = [UIColor whiteColor].CGColor;

14. 把头像设置为圆形， 设置圆角半径

    userImage.layer.cornerRadius = 27;//（27为正方形图片边长的一半）

    userImage.layer.masksToBounds = YES; //剪切多余部分

15.把图片的宽从0、高从10像素开始画，直到填充整个imgview，可以避免图片拉伸

   UIImage *img = [ImgView.imagestretchableImageWithLeftCapWidth:0topCapHeight:10];

    ImgView.image = img;

 16./****判断是否是第一次启动，用于设置第一次启动的启动页面****/

    //获取沙盒目录
    NSString *filePath = [NSHomeDirectory() stringByAppendingPathComponent:@"Documents/wx47.plist"];
    //区分第一次启动还是以后启动的
    NSDictionary *dic = [NSDictionary dictionaryWithContentsOfFile:filePath];
    if (dic == nil) {
        //第一次运行
        [self _initFirstOpenView];
        dic = @{@"first": @"YES"};
        //把一个字典写入到文件
        [dic writeToFile:filePath atomically:YES];

    }

17.清除缓存

- (void)_countCacheSize

{
    //获取应用程序的沙盒路径
    NSString *homePath = NSHomeDirectory();
//    NSLog(@"homePath is %@", homePath);
   
    //拼接出缓存路径
    NSString *imgPath = [homePath stringByAppendingPathComponent:@"Library/Caches/default/com.hackemist.SDWebImageCache.default"];
   
    //文件管理助手（管家）---->单利对象
    NSFileManager *fileManager = [NSFileManager defaultManager];
   
    //取得一个文件夹下所有的文件路径
    NSError *error = nil;

    NSArray *subPath = [fileManager subpathsOfDirectoryAtPath:imgPath error:&error];

   
    long long sum = 0;
   
    for (NSString *filePath in subPath) {
        //取得一个文件的路径
        NSString *path = [imgPath stringByAppendingPathComponent:filePath];
       
        //拿到文件的属性
        NSDictionary *attributes = [fileManager attributesOfItemAtPath:path error:&error];
       
        //取出文件的大小
        NSNumber *filesize = attributes[NSFileSize];
       
        sum += [filesize longLongValue];
       

    }

   
    cacheSize = sum / (1000.0 * 1000);
    NSLog(@"cacheSize is %.2f", cacheSize);
   

}

- (void)tableView:(UITableView *)tableView willDisplayCell:(UITableViewCell *)cell forRowAtIndexPath:(NSIndexPath *)indexPath
{
    if (indexPath.row == 0) {
        [self _countCacheSize];
        UILabel *label = (UILabel *)[cell viewWithTag:100];
        label.text = [NSString stringWithFormat:@"%.1fM", cacheSize];
    }

}

- (void)tableView:(UITableView *)tableView didSelectRowAtIndexPath:(NSIndexPath *)indexPath
{
    if (indexPath.row == 0) {
        //弹出清除对话框
        UIAlertController *alertCtrl = [UIAlertController alertControllerWithTitle:@"清空缓存" message:@"确定要清空缓存" preferredStyle:UIAlertControllerStyleAlert];
       
        UIAlertAction *cancleAction = [UIAlertAction actionWithTitle:@"取消" style:UIAlertActionStyleCancel handler:nil];
       
        UIAlertAction *sureAction = [UIAlertAction actionWithTitle:@"确定" style:UIAlertActionStyleDefault handler:^(UIAlertAction *action) {
            //确定清空缓存

            [[SDImageCache sharedImageCache] clearDisk];

           
            //刷新tableView
            [self.tableView reloadData];
           
        }];
       
        [alertCtrl addAction:cancleAction];
        [alertCtrl addAction:sureAction];
        [self presentViewController:alertCtrl animated:YES completion:nil];
    }

}

- (void)viewWillAppear:(BOOL)animated
{
    [super viewWillAppear:animated];
    //刷新tableView
    [self.tableView reloadData];

}

18.label宽度自适应

- (CGSize)labelAutoCalculateRectWith:(NSString*)text FontSize:(CGFloat)fontSize MaxSize:(CGSize)maxSize
{
   
    NSMutableParagraphStyle* paragraphStyle = [[NSMutableParagraphStyle alloc]init];
   
    paragraphStyle.lineBreakMode = NSLineBreakByWordWrapping;
   
    NSDictionary* attributes =@{NSFontAttributeName:[UIFont systemFontOfSize:fontSize],NSParagraphStyleAttributeName:paragraphStyle.copy};
   
    CGSize labelSize = [text boundingRectWithSize:maxSize options:NSStringDrawingUsesLineFragmentOrigin | NSStringDrawingUsesFontLeading | NSStringDrawingTruncatesLastVisibleLine attributes:attributes context:nil].size;
   
    labelSize.height = ceil(labelSize.height);
   
    labelSize.width = ceil(labelSize.width);
   
    return labelSize;
   

}