Objective-c (XCODE7) new features

• nullability

The nullability attribute is used to indicate whether the pointer can be nil, and the intent of the API can be expressed more clearly by this feature.

At the same time, the compiler nullability the code at compile time, prompting the necessary warnings.

To be added to Ns_assume_nonnull_begin when using ... Between Ns_assume_nonnull_end

Object pointers: Nullable nonnull

C-pointer: __nonnull __nullable __null_unspecified

Null_resettable is used in attributes, the setter method that represents the property can be set to the Nil,getter method and does not return nil

• Lightweight generics

Lightweight is because this is a pure compiler syntax support (LLVM 7.0), like nullability, without any OBJC runtime upgrades, that is, this new syntax can be used on Xcode 7 and fully backwards compatible (lower IOS version)

Mainly used in Nsarray and nsdictionary containers.

An array object that holds only the string object:

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A Dictionary object that only exists for numeric objects:

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To customize a container that supports generics:

@interface Stack <StackType>: nsobject-(void) Pushobject: (Stacktype) obj;-(stacktype) popobject; @end

• __kindof

Such as:

__kindof Amperson * p;

Object used to indicate that the pointer is storing a Amperson object or a Amperson subclass

Resolves problems with poor readability before using ID types, and adds legitimacy validation

This article is from the "Teacheran" blog, make sure to keep this source http://annmeng.blog.51cto.com/3321237/1745638

Objective-c (XCODE7) new features