iOS Summary _ios Development section Syntax simplified notation

The following simplified notation is a new formulation after IOS6.0

NSNumber

//simplification of the previous wording:

NSNumber *value1;

value1 = [nsnumbernumberwithint:12345];

value1 = [nsnumbernumberwithfloat:123.45f];

value1 = [nsnumbernumberwithdouble:123.45];

value1 = [nsnumbernumberwithbool:YES];

//Simplified wording:

NSNumber *value2;

value2 =@12345;

value2 =@123.45f;

value2 =@123.45;

value2 =@YES;

the//boxing expression can also be written in a similar way:

nsnumber *pioversixteen1 = [nsnumbernumberwithdouble: ( m_pi / +)];

nsstring *path1 = [nsstringstringwithutf8string: getenv( "PATH")];

//Can be abbreviated as:

nsnumber *pioversixteen2 = @ ( m_pi / +);

nsstring *path2= @ (getenv("PATH"));

//For string expressions, it is important to note that the value of an expression must not be null, or an exception will be thrown.

Nsarray

//For Nsarray initialization, there are a lot of writing, here is no longer one by one listed, we directly look at the new wording

Nsarray *array;

Array =@[]; //Empty array

Array =@[ a ]; //An array of objects

Array =@[ A, B, C ]; //array of multiple objects

//When the compiler is processing:

Array =@[ A, B, C ];

//compiler-generated code:

ID objects[] = {A, b, c};

Nsuinteger count = sizeof(objects)/ sizeof(ID);

Array = [nsarrayarraywithobjects: Objects count: Count];

//Note that if the A,b,c object has nil, the runtime throws an exception, which is different from the original processing, so be careful when coding.

Nsdictionary

Also, for a dictionary of this data structure, there are many ways to initialize, we look at the new wording:

nsdictionary *dict;

Dict =@{}; //Empty dictionary

Dict =@{@ "Key1":@ "value1"}; //Dictionary containing a key-value pair

dict = @{@ "Key1" : @ "value1",@ "Key2" : @ "value"@ "Key3" : @ " Value3 "}; //Dictionary with multiple key-value pairs

//The container constructed using the above notation is immutable, and if you need to generate a mutable container, you can pass the-mutablecopy message. For example

nsmutablearray *mutableplanets = [@[

@ " Mercury", @ "Venus",@ "Earth",

@ " Mars", @ "Jupiter",@ "Saturn",

@ "Uranus", @ "Neptune"

] mutablecopy];

nsmutabledictionary *dic=[@{@ "Key1" : @ "value1"@ " Key2 " : @" value "@" Key3 " : @" Value3 "} mutablecopy ];

iOS Summary _ios Development section Syntax simplified notation