iOS study note

respondstoselector
instancerespondstoselector
forwardingtargetforselector
resolveinstancemethod
resolveclassmethod
load

objc_getassociatedobject/set
objc_getClassList

imp_implementationWithBlock

class_getName
class_getmethod(class,instance)/addmethod/	replacemethod
class_copymethodlist
class_copypropertylist/property_getname

method_getTypeEncoding
method_getimplementation
method_exchange

NSURL
scheme
host
port
path
parameter
query
fragment

NSLog->__FILE__ __func__ __LINE__, _cmd,self
LogData/Image->Image或者Data->Boujour
base64 编码图片 Pros and Cons
图片无需再次请求
无法缓存

classdump ./App.app > api.txt
print property,method list of a objective-c app

dwarfdump --uuid dsym/app file <get a uuid>
crashlog -> indident identifier (They two would be 	exactly the same.)
To analyze crash logs, we have two options:
1.Readable crash callstack.
2.Combine the crash log with the dsym file.(dwarfdump 	command)
--uuid & --lookup

- fobjc-arc/fno-objc-arc single file enable/disable 	ARC
- MRC & ARC -> Reference counting.Compiler add 	retain/release when needed.
- Efficiency may be better than MRC.(Add release/	autorelease to realize MRC, maybe some opimization)

- Use xib for constraints
- Use Code <NSLayoutConstraint>
- Use Visual Formatted Language

Pros
- Runtime (mini and powerful)
- Base on C (current compile compatible and lots of library available)
Cons
- Garbage collection
- Namespace
- Operator override
- Multiple inheritance
- Dynamic type make it hard for compiler optimization

- all data types, class,method could be expressed in ASCII encoded string.
- No need to link it in the build phases
- if referenced, will be copyed,otherwise do nothing
- can add specific file.

- UIView animation over Core Animation Over Core Graphics
- UIView animation:duration delay option curve animationblock completionblock
- CoreAnimation:CABasicAnimation、CAKeyFrameAnimation、CAAnimationGroup(duration\timingfunction\values\fromvalue\tovalue\delegate\strong)
- CoreAnimation focus on content vs CoreGraphics focus on vector view.

- They are both based on Observer Pattern
- KVO is implemented by NSObject while Notification is implemented in NSNotification
- KVO is ofter used to observe value change while notification is used for some accident.
- [NSNotificationCenter defaultCenter] addobserver:selector:name:object
- Object addObserver:forKeyPath:options:context:
- It is possible to use delegates array with key of(notificationname,keypath,etc)
- Notification and KVO are 1->multiple need to be removed(not easy to trace,third party participated)
- KVO(string,refactor will make it not work,only one method with multiple ifs,remove)
- Delegate is 1->1,need to be set to nil(1->1,delegate nil)

- For task-based concurrency model
- NSOperation Queue is OC level,GCD is C level.
- NSOperation is internal implemented with GCD
- If you want to simply use a block , no need for high-level abstract(cancel,number limits,dependency) use GCD, otherwise use NSOperationQueue. 		dispatch_after,dispatch_async,dispatch_once,dispatch_group,dispatch_wait,dispatch_notify
- NSOperationQueue high-level abstract,make it 	little work for limit control,cancel,dependency;If 	you only need to use a block, no need for the 	additional advantages, use GCD.

Function pointer
Have access to outer variables Function & Enviroment
Object
Global & Stack & Heap
Block->Global,Stack(Using any local variable) BlockCopy(Stackblock->HeapBlock)
- Block retain,release,copy->retaincount always be 1
- Local auto object -> copy
- static,global object -> address
- OC object -> address
- static,global,non-oc object -> won't retain
- local object,self.xxx object -> will retain
- to make a object to be editable in a block, use 	__block to make it like static,global
- In MRC,__block won't retain, in ARC, __block will retain.
- Don't release a object when it is still in use(crash) and don't retain a object when it is no use(retain cycle).Avoid retain cycle.

- Model
- Context
- Coordinator(Model ->persistence Type,URL)
- Insert -> NSEntityDescription insertNewObjectForEntityForName:inManagedObjectContext: 	Save
- Fetch -> NSEntityDescription entityForName:inManagedObjectContext: Request setEntity: Context Fetch Request
- Concurrency -> Coordinator shared, Context mergeusing notification.

- Event Handling Runloop
- InputSource & Timer
- Timer Schedule -> add to current runloop/Default Mode
- Other timer, addtimer formode:
- In a thread, you have to manually start the runloop.
- NSStream,NSURLConnection->Runloop needed; First create a request, then scheduleinrunloop:formode,start request.
- NSRunloopCommonMode(NSRunloopDefaultMode,) 
1.Harm->Timer(schedule->add to current runloop in defaultmode,otherwise,you may have to add it in current runloop with specific mode.)
2.Timer & Events, 
3.Runloop runMode:beforeDate
4.NSURLConnection,NSStream->YES->DefaultMode,UITrackingRunloopMode will be sorry.NO->start:NO,schedule:CommonMode(Default,Tracking),start manually.
InputSource:Timer,Selector,Port,CustomSrc.

- Context 上下文
- Model 数据模型
- Coordinator 
- NSManagedObject
- Storage

- Safari is a good web browser, but consumes a lot of memory.
- CoreText a great rendering engine.
- Context
- AttributedString
- CTFrameSettingref
- CTFrame(CGPath、VisibleRange)
- Draw
- Transform

- CIContext -> Options
- CIImage -> Content
- CIFilter ->Filter Processing.

- init -> lock
- dealloc -> unlock

- open -> NSURLProtocol -> register/scan decide / handle can initwithrequest
- iframe -> change src -> shouldstartloadwithrequest

- App Groups
- UserDefaults/ShareFile

- Create a snapshot view
- Pan Gesture Recognizer Delegate, move it.
- When finished,change datasource,update UI.

- Number
- Array
- Dictionary

- Button 排他点击 ExclusiveTouch  YES

- 构造器 (原型、抽象工厂、工厂方法、生成器、单例)
- 适配 （适配、桥接、外观）
- 解耦（观察者、中介者）
- 抽象集合 （组合、迭代器）
- 扩展 （访问者、装饰、责任链）
- 算法 （模板、命令、策略）
- 性能 （代理、享元）
- 对象状态 （备忘录）

- makeObjectsPerformSelector

- alloc new copy mutablecopy

- 触摸事件、传感器、远程控制
- Reponse Chain: UIView->SuperView->Controller/SuperView->Window->Application(处理机制)
- HitTest chain: Reverse.

read image data from source and write it into destination.

- they are one things.
- however,when super appears, runtime will use objc_msgSendSuper instead of objc_msgSend.

- Immutable
- Must be foundation objects.

Avoid preprocessor defines. No type information,just replace.
Global Constants.External and Define.

- Use Enumerations for States,Status,Options.
- NS_ENUM/NS_OPTIONS
- 2^power
- switch-default

- Class{@public NSDate *_dateOfBirth;NSString 	*firstName;NSString *_lastName;}
- [           Class]
- [+0         firstName]
- [+0         secondName]
- [+0         birthOfDate]

- assign
- strong
- weak
- unsafe_unretained
- copy

- @property -> data encapsulates
- atomic,nonatomic
- read using direct access and write using setter.(direct could be faster because there is no objc_msgSend like calls,by kvo will be bypassed,setter,debug.)
- Read directly, and write using setter.(faster/kvo,setter,debug)
- Equal(==,class,equalto,hash).
- Equal must have same hash, but objects with the same hash may not be equal.
- objc_get/set/remove associatedobjects
- id returnvalue = objc_msgSend(someobject,@selector(messageName),parameter)
- objc_msgSendSuper
- resolveInstanceMethod(class_addMethod) -> will be called.
- Message Forwarding
- 1.Resolve Instance Method(resolve class method)
- 2.forwardingTargetForSelector
- 3.forwardInvocation
- Message Forwarding happeds when a object is found not to be responding to a selector.
- Dynamic
- Forwarding Target
- Full Forwarding
- Selector Table:
- MethodName -> IMP
- Switch
- Exchange
- Method Swizzerling is often used for debug, not because it can.
- Method swizzling.
- class
- {
- isa
- super_class
- name
- version
- info 
- instance_size
- ivars
- methodlist
- caches
- protocols
- }