Some common classes in the COCOA Foundation framework

Today I learned some basic classes in the foundation framework that are often used in objective-c, including NSNumber (numbers, characters, etc.), nsstring (strings), Nsarray (arrays), nsdictionary (dictionaries, In fact, it is also a collection Class) and Nsset (collection) and so on. These classes are contained in the Foundation.h class library, and each class declares some very useful methods that they can think of as some basic data types in OC, so their importance is self-evident. The following is a summary of how they are used:

1, NSNumber

There are some basic data types in C, such as int, float, char, and so on, and the NSNumber class provided in OC can convert these basic types of data and objects into each other using the declared method to facilitate specific operations.

1) Basic type ===〉 object, there are two methods can be implemented, namely, class method and instance method:

Intnumr=1;

floatnum2=4.5;

Blloisbool=no;

Charc= ' C ';

class method implementation

Nsnumber*intnumber=[nsnumber Numberwithint:num];

Nsnumber*floatnumber=[nsnumber Numberwithfloat:float];

Example method implementation

Nsnumber*isboolnumber = [[NSNumber alloc] initwithbool:isbool];

Nsnumber*cnumber = [[NSNumber alloc] initwithchar:c];

Print

NSLog (@ "intnumber:%@", intnumber);

NSLog (@ "floatnumber:%@" floatnumber);

NSLog (@ "Isboolnumber:%@", isboolnumber);

2) Object ===〉 Basic type

int d = [intnumber intvalue];

float f1 = [Floatnumber floatvalue];

char C1 = [Cnumber charvalue];

NSLog (@ "%d,%f,%c", D,F1,C1);

2, NSString

NSString is the OC-heavy string type, which defines the object as a string object, and the format of the string object is @ "string content". Its method is used as follows:

String creation

String constants

NSString *str = @ "good. ";

Variable of string

1) Empty string creation

NSString *STR2 = [[NSString alloc] init];

STR2 = @ "Test";

NSString *STR3 = [NSString string];

NSLog (@ "str =%@,str2=%@,str3=%@", STR,STR2,STR3);

2) quickly create a string

NSString *STR4 = [[NSString alloc]initwithstring:@ "Hello"];

NSSTRING*STR5 = [NSString stringwithstring:@ "World"];

NSLog (@ "STR4 =%@,str5=%@", STR4,STR5);

3) formatting to create a string

NSString *STR6 = [[NSString alloc]initwithformat:@ "%d_%d_%d_%d_%d_%@", 1,2,3,4,5,STR4];

NSLog (@ "str6=%@", STR6);

Determine if strings are equal

if ([STR4 ISEQUALTOSTRING:STR5]) {

NSLog (@ "string equal");

}else{

NSLog (@ "string not Equal");

}

NSLog (@ "%p,%p", STR4,STR5);

Determine if a string is the same object

if (str4== str5) {

NSLog (@ "is the same object.) ");

}

Basic data type è string

STR =[[nsstring alloc] initwithformat:@ "%d", 5];

String ===〉 base data type

NSSTRING*STR7 = [NSString stringwithformat:@ "%d", 56];

int num7= [STR7 intvalue]; string-To-integer

NSLog (@ "num7+1=%d", num7+1);

string conversion è array

Nsarray*array = [Str6 componentsseparatedbystring:@ "_"];

NSLog (@ "%@", array);

String interception

NSLog (@ "Substringto 5:%@", [STR6 substringtoindex:5]);

NSLog (@ "Substringfrom 5:%@", [STR6 substringfromindex:5]);

To intercept a string of a range

Nsrangerang;

Rang.length= 4;

Rang.location= 2; When intercepted, contains the starting position

NSLog (@ "substring:%@", [STR6 Substringwithrange:rang]);

String lookup (Find substring)

nsstring*str8=@ "Hello01.txt";

Find, return range

NSRangerang2 = [Str8 rangeofstring:@ ""];

if (rang2.location!= nsnotfound) {

NSLog (@ "substr location =%ld, length=%ld", rang2.location,rang2.length);

}else{

NSLog (@ "nsnotfound!!");

}

Variable-length strings

NSMUTABLESTRING*MUTABLESTR = [nsmutablestring stringwithstring:@ "Love Rice"];

Dynamically inserted content

[mutablestrinsertstring:@ "Mouse" atindex:0];

NSLog (@ "mubablestr:%@", mutablestr);

3, Nsarray

In OC, the Nsarray class is equivalent to the array type in C, which is used to store an ordered list of objects, you can put objects of any class in the Nsarray object, Nsarray creates an array of immutable objects, so there is a supplemental class Nsmutablearray. This allows us to arbitrarily add and remove objects from the array. Their basic usage is as follows:

Define an array and initialize

Nsarray *array1 = [nsarrayarraywithobject:@ "one"];

Nsarray *array2 = [Nsarray arraywithobjects:@ "one", @ "one", @ "three", @ "four", nil];

Nsarray *array3 = [Nsarrayarraywitharray:array2];

NSLog (@ "array1 =%@, array2 =%@, Array3 =%@", array1,array2,array3);

Access to arrays

Request length

int len = [array2 count];

accessing elements

NSString *arrayobject = [Array3 objectatindex:3];

Concatenate array elements into a single string

NSString *newstr = [array2componentsjoinedbystring:@ "_"];

NSLog (@ "Array2 length:%d,index3=%@,joinstr =%@", len,arrayobject,newstr);

Use of variable groups

Nsmutablearray *mutablearray = [nsmutablearrayarraywithobjects:@ "One", nil];

----adding elements

[Mutablearray addobject:@ ""];

[Mutablearray addobject:@ "three"];

[Mutablearray addobject:@ "four"];

-------------Add an array

[Mutablearray Addobjectsfromarray:array2];

----Calculation length

int length = [Mutablearray count];

NSLog (@ "Mutablearray length=%d,countent:%@", Length,mutablearray);

----Remove the last

[Mutablearray Removelastobject];

----Remove the specified data

[Mutablearray removeobjectatindex:0];

length = [Mutablearray count];

NSLog (@ "***mutablearraylength=%d,countent:%@", Length,mutablearray);

How arrays are traversed: an efficient way of traditional methods

-----Traditional Way

for (int i=length-1; i>=0; i--) {

NSLog (@ "%d =%@", I,[mutablearray objectatindex:i]);

}

-----efficient way, it's important to note that the high-efficiency approach is a new feature that starts with objective-c2.0, and that if you or/your users need to run on a tiger (MAC OS X10.4) system, you can't use this new syntax, which is really/really bad.

For (NSString *str in Mutab learray) {

NSLog (@ "obj =%@", str);

}

4, Nsdictionary

The dictionary type of OC, which is the set of keywords and their definitions. Nsdictionary stores a numeric value (which can be any type of object) under a given keyword (usually a nsstring string). Then you can use this keyword to find the corresponding value.

-----initialization

NSNumber *numobj = [nsnumbernumberwithint:100];

Initialize a set of arrays

Value key

Nsdictionary *dic1 = [nsdictionarydictionarywithobject:numobj forkey:@ "Key1"];

Initializing multiple sets of data

nsdictionary*dic2=[nsdictionarydictionarywithobjectsandkeys:@ "Hello", @ "Key2", @ "World", @ "Key3", @ "csdn", @ "Key4", NIL];

Initialize another dictionary with a dictionary

Nsdictionary *dic3 = [Nsdictionarydictionarywithdictionary:dic2];

Print output

NSLog (@ "Dic1:%@,dic2:%@, Dic3:%@", DIC1,DIC2,DIC3);

------Get values

Get length

int len = [Dic2 count];

NSLog (@ "Dic2 length =%d", Len);

Gets the value corresponding to key from key

NSLog (@ "Key3 value =%@", [dic2objectforkey:@ "Key3"]);

Can get all the keys

Nsarray *allkeys = [dic3 AllKeys];

NSLog (@ "Nsarray allkey =%@", AllKeys);

You can get all the values

Nsarray *allvalues = [dic3 allvalues];

NSLog (@ "Nsarray allvalues =%@", allvalues);

-----variable Dictionaries

-----initialization

nsmutabledictionary*dic4=[nsmutabledictionarydictionarywithobjectsandkeys:@ "One", @ "Key4", @ "one", @ "Key5", nil];

NSLog (@ "DIC4:%@", DIC4);

Define an empty dictionary

Nsmutabledictionary *dic5 =[nsmutabledictionary Dictionary];

Add a whole dictionary dic2 to the DIC4

[Dic4 Addentriesfromdictionary:dic2];

NSLog (@ "Addentriesfromdictionary dic2:%@", DIC4);

Add an Element

[dic4setvalue:@ "three" forkey:@ "Key6"];

NSLog (@ "Dic4 setValue:%@", DIC4);

Get value based on key

NSLog (@ "Key6 =%@", [dic4objectforkey:@ "Key6"]);

------The traversal of a dictionary

1) General traversal

Nsarray *KEYS4 = [Dic4 AllKeys];

for (Inti=0;i<[dic4 count];i++) {

NSLog (@ "Dic4 key =%@,value=%@", [Keys4 objectatindex:i],[dic4 objectforkey:[keys4objectatindex:i]]);

}

2) Efficient for

For (NSString *key in Dic4) {

NSLog (@ "Dic4 key =%@, Value =%@", Key,[dic4 Objectforkey:key]);

}

3) using enumerations to traverse

Nsenumerator *enum1 = [Dic4 keyenumerator];

Gets the key, or offsets if it is not empty

ID key = [enum1 nextobject];

while (key) {

NSLog (@ "key=%@, value =%@", Key,[dic4 Objectforkey:key]);

Key =[enum1 Nextobject];

}

5, Nsset

The keyword for a collection object is Nsset and Nsmutableset, which is an immutable collection, which is a mutable collection. Nsset objects are similar to Nsarray object usages, but Nsset object access is slower and Nsarray objects are stored more quickly. Use the following:

-----definition, initialization

Nsset *set = [[Nsset alloc]initwithobjects:@ "one", @ "one", @ "one", nil];

Define nsset with an array;

Nsarray *arrayset = [nsarrayarraywithobjects:@ "1", @ "2", @ "3", nil];

Nsset *set2 = [Nsset setwitharray:arrayset];

NSLog (@ "Set1 =%@,set2 =%@", Set,set2);

Access mode

-----Get length

int len = [Set2 count];

NSString *s = [Set2 anyobject];

NSLog (@ "Set2 length =%d,obj =%@", len,s);