(5/18)重学Standford_iOS7开发_视图控制器生命周期_课程笔记

@PRoperty (nonatomic, readonly) NSTextStorage *textStorage;//注意为只读属性，因此不能直接更改内容，NSTextStorage为NSMutableAttributeString的子类，因此可以更改字符串属性内容（而非字符串）//例如，添加属性[self.body.textStorage addAttribute:NSForegroundColorAttributeName                                  value:sender.backgroundColor                                  range:self.body.selectedRange];@property (nonatomic, strong) UIFont *font;//例如添加字体self.body.font = [UIFont preferredFontForTextStyle:UIFontTextStyleBody];    self.headLine.font = [UIFont preferredFontForTextStyle:UIFontTextStyleHeadline];//文本布局功能，如图文混排等@property (readonly) NSTextContainer *textContainer;@property (readonly) NSLayoutManager *layoutManager;

- (instancetype)initWithNibName:(NSString *)name bundle:(NSBundle *)bundle;//非storyboard加载方式，指定初始化器- (void)awakeFromNib;//从storyboard中加载UI时调用，此时未设置输出口//设置输出口- (void)viewDidLoad;//可以放置控制器初始化代码（一次性），如init。不可放置与几何相关的代码，此时控制器中的UI边界未确定//确定几何布局//当视图frame发生变化时就会被调用，此处适合添加与几何相关的代码- (void)viewWillLayoutSubviews;- (void)viewDidLayoutSubviews;//其他关于屏幕旋转等API...- (void)viewWillAppear:(BOOL)animated;//生命周期中可能会被反复调用，因此不能放置一次性初始化内容- (void)viewDidAppear:(BOOL)animated;- (void)viewWillDisappear:(BOOL)animated;//可以进行一些当前数据保存工作- (void)viewDidDisappear:(BOOL)animated;- (void)didReceiveMemoryWarning;//系统在内存不足时调用

[NSNotificationCenter defaultCenter];//获取defaultCenter//添加观察者- (void)addObserver:(id)observer //接收通知的对象                  selector:(SEL)methodToInvokeIfsomethingHappens                     name:(NSString *)name //广播名                    object:(id)sender; //监听的广播对象，nil指监听所有对象//接收到通知后调用方法- (void)methodToInvokeIfSomethingHappens:(NSNotification *)notification{    notification.name // the name passed above    notification.object //发送广播的对象    notification.userInfo // notification-specific information about what happened（取决于发送者）}//结束收听通知，通常放于视图从界面消失时[center removeObserver:self];[center removeObserver:self name:UIContentSizeCategoryDidChangeNotification object:nil];    

//视图出现在屏幕上注册通知- (void)viewWillAppear:(BOOL)animated{    [super viewWillAppear:animated];    [[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(preferredFontChanged:) name:UIContentSizeCategoryDidChangeNotification object:nil];}//通知出现时调用方法- (void)preferredFontChanged:(NSNotification *)notification{    [self usePreferredFonts];}//重新设置字体- (void)usePreferredFonts{    self.body.font = [UIFont preferredFontForTextStyle:UIFontTextStyleBody];    self.headLine.font = [UIFont preferredFontForTextStyle:UIFontTextStyleHeadline];}//视图离开界面是移除通知- (void)viewWillDisappear:(BOOL)animated{    [super viewWillDisappear:animated];    [[NSNotificationCenter defaultCenter] removeObserver:self                                                    name:UIContentSizeCategoryDidChangeNotification                                                  object:nil];