waiting

    self.subcategoryTableView.contentInset = UIEdgeInsetsMake(64, 0, 0, 0);

• 网络下载图片失败的解决

• SDWebImage的图片缓存周期是多长:1个星期 - [cell.imageView sd_setImageWithURL:[NSURL URLWithString:app.icon] placeholderImage:[UIImage imageNamed:@"placeholder"] options:0 progress:^(NSInteger receivedSize, NSInteger expectedSize) {

    // expectedSize: 图片的总字节数
    // receivedSize: 已经接收的图片字节数
  
    NSLog(@"下载进度：%f", 1.0 * receivedSize / expectedSize);
  

  } completed:^(UIImage image, NSError error, SDImageCacheType cacheType, NSURL *imageURL) {

    NSLog(@"下载完图片");
  

  }];

  1.官方框架 2.自己写的框架 3.第三方框架 1> 隐患

  • 怕框架有BUG
  • 怕框架停止更新
  • 怕作者不及时更新 2> 好处
  • 简单易用
  • 更加稳定
  • 大大提高开发效率

  Masonry SDWebImage

  CocoaPods：第三方框架管理工具

利用苹果官方API播放视频

// 创建视频播放器
MPMoviePlayerViewController *vc = [[MPMoviePlayerViewController alloc] initWithContentURL:[NSURL URLWithString:urlStr]];

// 显示视频
[self presentViewController:vc animated:YES completion:nil];

• markdown:标记语言，语法，可以让普通文本变成好看的格式，例如简书

运行时

[UINavigationBar appearance];

    // 通过appearance统一设置所有UITabBarItem的文字属性
    // 后面带有UI_APPEARANCE_SELECTOR的方法, 都可以通过appearance对象来统一设置
    NSMutableDictionary *attrs = [NSMutableDictionary dictionary];
    attrs[NSFontAttributeName] = [UIFont systemFontOfSize:12];
    attrs[NSForegroundColorAttributeName] = [UIColor grayColor];

    NSMutableDictionary *selectedAttrs = [NSMutableDictionary dictionary];
    selectedAttrs[NSFontAttributeName] = attrs[NSFontAttributeName];
    selectedAttrs[NSForegroundColorAttributeName] = [UIColor darkGrayColor];

    UITabBarItem *item = [UITabBarItem appearance];
    [item setTitleTextAttributes:attrs forState:UIControlStateNormal];
    [item setTitleTextAttributes:selectedAttrs forState:UIControlStateSelected];

    // 更换tabBar
//    self.tabBar = [[XMGTabBar alloc] init];
    [self setValue:[[XMGTabBar alloc] init] forKeyPath:@"tabBar"];

//- (CGFloat)x;
//- (void)setX:(CGFloat)x;
/** 在分类中声明@property, 只会生成方法的声明, 不会生成方法的实现和带有_下划线的成员变量*/

#ifndef _1_______PrefixHeader_pch
#define _1_______PrefixHeader_pch

#import "UIView+XMGExtension.h"

#ifdef DEBUG
#define XMGLog(...) NSLog(__VA_ARGS__)
#else
#define XMGLog(...)
#endif

#define XMGLogFunc XMGLog(@"%s", __func__)

#endif

 24bit颜色: R G B
 * #ff0000
 * #ccee00
 * #000000
 * #ffffff

 32bit颜色: ARGB
 * #ff0000ff

 常见颜色:
 #ff0000 红色
 #00ff00 绿色
 #0000ff 蓝色
 #000000 黑色
 #ffffff 白色

 灰色的特点:RGB一样

 1024x1024像素的图片  32bit颜色

// 文字属性
    NSMutableDictionary *attrs = [NSMutableDictionary dictionary];
    attrs[NSForegroundColorAttributeName] = [UIColor grayColor];

    // NSAttributedString : 带有属性的文字(富文本技术)
    NSAttributedString *placeholder = [[NSAttributedString alloc] initWithString:@"手机号" attributes:attrs];

```objc

```objc
/**

• 让当前控制器对应的状态栏是白色 */
  • (UIStatusBarStyle)preferredStatusBarStyle { return UIStatusBarStyleLightContent; } ```

 NSString *key = @"CFBundleShortVersionString";

    // 获得当前软件的版本号
    NSString *currentVersion = [NSBundle mainBundle].infoDictionary[key];
    // 获得沙盒中存储的版本号
    NSString *sanboxVersion = [[NSUserDefaults standardUserDefaults] stringForKey:key];

    if (![currentVersion isEqualToString:sanboxVersion]) {
        UIWindow *window = [UIApplication sharedApplication].keyWindow;

        XMGPushGuideView *guideView = [XMGPushGuideView guideView];
        guideView.frame = window.bounds;
        [window addSubview:guideView];

        // 存储版本号
        [[NSUserDefaults standardUserDefaults] setObject:currentVersion forKey:key];
        [[NSUserDefaults standardUserDefaults] synchronize];
    }

```objc
// 让按钮内部的label根据文字内容来计算尺寸
        [button.titleLabel sizeToFit];
        ```

    // 不要自动调整inset
    self.automaticallyAdjustsScrollViewInsets = NO;

- (IBAction)save {
    // 将图片写入相册
    UIImageWriteToSavedPhotosAlbum(self.imageView.image, self, @selector(image:didFinishSavingWithError:contextInfo:), nil);
}

- (void)image:(UIImage *)image didFinishSavingWithError:(NSError *)error contextInfo:(void *)contextInfo
{
    if (error) {
        [SVProgressHUD showErrorWithStatus:@"保存失败!"];
    } else {
        [SVProgressHUD showSuccessWithStatus:@"保存成功!"];
    }
}