Thoughts on objective-C during winter vacation

I bought this book "Learn objective-C on Mac". At the beginning, I bought a 250 page that looks quite thin. After reading it, I found that there are many common languages, the new features are all similar to those in C ++ and Java, that is, a new name. After reading the new features, I feel that I have gained a lot of attention, although I have only touched on a bit of fur.

1. Knowledge of C Language

2. Understand how to use xcode

3. understand some New syntaxes and new features.

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1. Formal and informal protocols (replaced by the official @ Optional Protocol) and file loading and storage

@ Required must be implemented

@ Optional selective implementation

 

Example 1.

@ Protocol nscopying // deep Replication

-(ID) copywithzone :( nszone *) zone;

@ End

 

Copy of nsarray is a light copy.

 

@ Protocol nscoding // encoding and decoding

-(Void) encodewithcoder :( nscoder *) ACO;

-(ID) initwithcoder :( nscoder *) decoder;

 

Nscoding can be used to encode any object as nsdata. Available [data writetofile: "tmp.txt" atomically: True] stored on hard disk

 

Example 1:

@ Interface A: nsobject <nscopying, nscoding> </P> <p >{</P> <p> nsstring * Name; </P> <p >}</P> <p> @ property (copy) nsstring * Name; </P> <p> @ end </P> <p> @ implementation a </P> <p> @ synthesize name; </P> <p>-(ID) copywithzone :( nszone *) Zone <br/>{</P> <p> A *; <br/> A = [[self class] allocwithzone: Zone] init]; <br/>. name = self. name; <br/> return a; <br/>}</P> <p>-(void) encodewithcoder :( nscoder *) ACO der <br/>{< br/> [ACO der codewithobject: Name forkey: @ "name"]; <br/>}< br/>-(ID) initwithcoder :( nscoder *) decoder <br/>{< br/> If (Self = [Super init]) <br/>{< br/> nsstring * n = [decoder decodeobjectforkey: @ "name"]; </P> <p >}< br/> return self; <br/>}< br/>

 

The nskeyedarchiver class is encoded as nsdata.

Nsdata * Data = [nskeyedarchiver archiveddatawithrootobject: object]; automatic call of encodewithcoder

 

A * A = [nskeyedunarchiver unarchiveobjectwithdata: Data]; // decode

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Attribute list nsarray nsdictionary nsstring nsnumber nsdate nsdata

1. nsarray

+ (ID) arraywithobject:... ends with nil

-(Unsigned) count;

-(ID) objectatindex :( unsigned) index;

 

Nsmutablearray

+ (ID) arraywithcapacity :( INT );

-(Void) addobject :( nsobject );

-(Void) removeobjectatindex :( INT) index;

2. nsdictionary

+ (ID) dicitonarywithobjectsandkeys :( ID) firstobject, (nsstring *) firstkey ...;

-(ID) objectforkey :( ID) Key;

 

Nsmutabledictionary

+ (ID) dicitonarywithcapacity :( INT) N;

-(Void) setobject :( ID) object forkey :( ID) Key;

-(Void) removeobjectforkey :( ID) Key;

 

3. nsnumber

Encapsulation standard type

Nsnumber * A = [nsnumber numberwithint: 10];

4. nsdate

+ (Nsdate *) date;

+ (Nsdate *) datewithtimeintervalsincenow :( INT);

5. nsdata

+ (Nsdata *) datawithbytes :( nsobject) length :( INT );

-(INT) length;

-(Nsobject) bytes;

 

 

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Predicate:

In fact, a predicate can be replaced by a for or if clause in a simple way.

Nspredicate:

+ (Nspredicate) predicatewithformat :....

-(Nsarray *) filteredarrayusingpredicate: predicate;

Example:@ Interface A: nsobject <br/>{< br/> nsstring * Name; <br/>}< br/> @ property nsstring * Name; <br/> @ end <br/> @ implementation a <br/> @ synthesize name; <br/> @ end <br/> @ interface B; nsobject <br/>{< br/> nsmutablearray * A; <br/>}< br/> @ end <br/> @ implementation B <br/>-(void) adda (nsstring * n) <br/>{< br/> A * object; <br/> object. name = N; <br/>. add (object); <br/>}< br/> @ end <br/> int main () <br/>{< br/> B * bobject = [[B alloc] init]; <br/> bobject. adda ("A"); <br/> bobject. adda ("B"); <br/> bobject. adda ("C"); <br/> bobject. adda ("D"); <br/> nspredicate * predicate = [nspredicate predicatewithformat: @ "name = % @", "a"]; <br/> nsarray * result = [bobject filteredarrayusingpredicate: predicate]; </P> <p>}

 

A lot of operators are returned for the predicate (which can follow the C Operator)

For example, the class of the example is used.

Nspredicate * predicate = [nspredicate predicatewithformat: @ "(name = 'A') and (name = 'B')"];

 

Array Operator name between {min, max };

Name in {"A", "B "};

Use of self:

Nsarray * A = [nsarray arraywithobject: @ "A", "B", nil];

Nspredicate * predicate = [nspredicate predicatewithformat: @ self in "'A', 'B'"];

Nsarray * B = [A filteredarrayusingpredicate: predicate];

 

String OPERATOR:

Beginswith

Endswith

Contains

 

[C] case-insensitive

[D] Ignore duplicate notes

All [cd] are ignored.

Example: beginswith [c]

 

 

Like Operator

Like '* a' contains.

Like '?? A * 'has two characters in front