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Notes on data Structures and Algorithms

Notes for geek Time iOS Developer Class

IOS large factory interview high frequency algorithm summary

Summary of iOS interview materials

classification

What do you do with classification?

  • Declare private methods
  • Decompose large class files
  • Expose the Framework’s private methods

Second, the characteristics of classification

  • Runtime resolution
  • You can add categories to system classes

Three, classification can be added to what content?

  • Instance methods
  • Class method
  • agreement
  • attribute

Four, classified source code interpretation

  • This section of notes is the same as the Category mentioned by Junior brother, and junior brother’s class is more detailed, so here is a direct link to junior brother’s Category notes.

Day 5: Category

associations

Can I add “member variable” to the classification?

  • You can add member variables to a classification using the “associative object” technique.

Two, associated object source code

Day 7: Associate objects

extension

What do extensions do in general?

  • Declare a private property
  • Declare private methods
  • Declare private member variables

Ii. The difference between classification and extension?

  • classificationisRuntime resolution.extensionisCompile-time resolution.
  • Classifications can be declared and implemented. Extensions exist only as declarations, mostly in the.m of the host class.
  • You can add categories to system classes, but not extensions to system classes.

The agent

  • A piece of software, to be exactDesign patterns.
  • Among the iOS to@protocolForm manifests.
  • Delivery mode one to one.

How to avoid circular reference?

notice

  • Is the use ofObserver modelTo implement a mechanism for sending messages across layers.
  • The transmission mode isMore than a pair of.

How to implement notification mechanism?

  • Global dictionaryNotification_MapIn order tonotificationNameforkeyTo the arrayObservers_Listforvalue.
  • Observers_ListSave all statements the samenotificationNameThe object.
  • Object toObserverThe form of preservation, which includesFunction executed.objectItself, etc.

KVO

Day 4: The essence of KVO

KVC

Day 5: The essence of KVC

Attribute keyword

  • Read and write access
    • readonly
    • readwrite
  • atomic
    • atomic
    • nonatomic
  • Reference counting
    • retain/strong
    • assign/unsafe_unretained
    • weak
    • copy

Are atomic thread-safe?

  • atomicModify the object that the system will apply to itset,getFunction to lock.
  • ifatomicDecorates an array, then assigns to the arraysetAnd access togetIt can be guaranteedThread safety.
  • If I take an arrayAdd elementsandRemove elementsOperation, is notatomicWithin the operating range of, yesThread insecurity.

Atomic

Ii. What is the difference between assign and weak?

  • assign
    • Modifies basic data types, such asint,boolAnd so on.
    • When an object type is modified, its reference count does not change.
    • It produces a dangling pointer.
  • weak
    • Does not change the reference count of the back modifier object.
    • The object is automatically set to when it is releasednil.

The difference between shallow copy and deep copy?

Day 25: OC object memory management

Objective-c interview summary

  • How to override setter methods for retain decorates variables under MRC?

  • Please briefly describe the implementation principle of classification.
  • How does KVO work?
  • Can I add a member variable to a classification?