iOS Review Note 14: Common data structures and the like

A nsstring/nsmutablestring string
1 nsstring

<pre name= "code" class= "OBJC" >nsstring* S1 = @ "string";//nsstring* s2 = [[NSString alloc] Initwithformat (@ "%d is one ", 1)]; nsstring* s2 = [NSString stringWithFormat (@ "%d is one", 1)];//C language strings and OC strings convert each other//nsstring* OS = [[NSString alloc] Initwith Utf8string: "C String"]; nsstring* OS = [NSString stringwithutf8string: "C String"];const char* cs = [OS utf8string]; Initialize string with file content//nsstring* s3 = [[NSString alloc] initwithcontentsoffile:@ "file absolute path"//encoding:nsutf8stringencoding//In Text code//ERROR:NIL]; nsstring* s3 = [nsstring stringwithcontentsoffile:@ "File absolute path" encoding:nsutf8stringencoding//Chinese encoding error:nil];//url:/// Resource path//protocol header:///resource path//file:///resource Path//ftp:///resource path//nsurl* URL = [[Nsurl alloc] initwithstring:@ "file://path"]; nsurl* url = [nsurl urlwithstring:@ "file://path"];//nsstring* s6 = [[NSString alloc] initwithcontentsofurl:url//encoding: nsutf8stringencoding//Chinese code//Error:nil]; nsstring* s6 = [NSString stringWithContentsOfURL:urlencoding:NSUTF8StringEncoding//Chinese code Error:nil];//String split nsarray* arr = [@ "one|two|three|four|five" componentsseparatedbystring:@ "|"] Write file [s1 writetofile:@ "file path" Atomiccally:yes encoding:nsutf8stringencoding Error:nil]; [S1 WriteToURL:urlatomiccally:YES encoding:nsutf8stringencoding Error:nil]; nsstring* Strnum = @ "ten"; int n = [Strnum intvalue];

Subclass of 2 Nsmutablestringnsstring

nsmutablestring* ms1 = [nsmutablestring stringwithformat:@ "My age is 10"];//add string [ms1 appendstring:@ "or 13"];//no return value, modify M The value of S1 itself//delete string Nsrange RG = [S1 rangofstring:@ "age"]; [Ms1 DELETECHARACTERSINRANGE:RG]; nsstring* ns1 = @ "my age"; nsstring* ns2 = [ns1 stringbyappendingstring:@ "is 10"];//returns a new string without modifying the value of NS1

Two sets of classes
1 Nsarray/nsmutablearray Array
OC arrays can only hold OC objects and cannot hold the underlying data type and nil

Nsarray: Immutable group nsmutablearray: variable array//array creation nsarray* ARR1 = [Nsarray array]; nsarray* arr2 = [arraywithobject:@ "name"];//nil array element end flag nsarray* ARR3 = [arraywithobjects:@ "name" @ "id", nil]; nsarray* ARR4 = @[@ "One", @ "one", @ "three", @ "four"];//array elements unsigned long count1 = [Arr3 count];unsigned long count2 = ARR3 . count;//array element Access nsstring* e1 = [Arr3 objectatindex:1]; nsstring* e2 = arr3[0];//array traversal for (int i = 0; i < Arr4.count; ++i) {arr4[i];} for (id obj in arr4) {obj;    [Arr4 indexofobject:obj];//gets the subscript of the array}[arr4 enumerateobjectsusingblock:^ (id obj, Nsuinteger idx, BOOL *stop) {if (idx = = 1) {*stop = yes;//jumps out of traversal}}];/ /variable array nsmutablearray* marr = [[Nsmutablearray alloc] init];; [Marr addobject:@ "one"]; [Marr addobject:@ ""]; [Marr addobject:@ "three"];//variable array-delete [Marr removeobject:@ "one"]; [Marr removeobjectatindex:0]; [Marr Removeallobjects];

2 Nsset/nsmutableset Collection
Only OC objects can be stored, cannot hold the underlying data type and hold nil

nsset* ST1 = [Nsset set]; nsset* st2 = [Nsset setwithobject:@ "one"]; nsset* ST3 = [Nsset setwithobjects:@ "one", @ "a", nil];//randomly takes out an object nsstring* ssobj = [St3 anyobject]; nsmutableset* mst = [Nsmutableset set]; [MST addobject:@ "three"];//delete [MST removeobject:@ "one"]; [MST removeallobjects];3 nsdictionary/nsmutabledictionary Dictionary//create nsarray* keys = @[@ "name" @ "Address"]; nsarray* OBJS = @[@ "June", @ "China"]; nsdictionary* Dict1 = [nsdictionary dictionarywithobjests:objs Forkeys:keys]; nsdictionary* dict2 = [nsdictionary dictionarywithobjestsandkeys:@ "name", @ "June", @ "address", @ "China", nil]; nsdictionary* dict3 = @{@ "name": @ "June", @ "address": @ "China"};//variable dictionary nsmutabledictionary* msdict = [nsdictionary dictionary];//add element [Dict1 setobject:@ "June" forkey:@ "name"]; [Dict1 setobject:@ "Hanfeng" forkey:@ "name"];//overwrite the previous value//remove [Dict1 removeobjectforkey:@ "name"];//Access id obj1 = [dict1  objectforkey:@ "Name"];id obj2 = dict1{@ "name"}//get the number of key-value pairs int count = dict1.count//Get all the key values and then traverse this array nsarray* ks = [Dict1 AllKeys]for (int i = 0; i < Dict1.count; ++i) {id k = Keys[i];id v = dict1[k];//[dict1 objectforkey:k];} [Dict1 enumeratekeysandobjectsusingblock:^ (id key,id obj, BOOL *stop) {//Key, obj}];

The above three classes (Nsarray, Nsset, nsdictionary) are called collection classes
Nsarray/nsmutablearray
* Orderly
* Quick Create: @[obj1,obj2,...]
* Quick access: array name [i]


Nsset/nsmutableset
* Unordered


Nsdictionary/nsmutabledictionary
* Unordered
* Quick Create: @{key1:value1,key2:value2,...}
* Quick access: Dictionary name {key}


Three nsvalue/nsnumber numbers
1 Nsvalue
Wrapping other data types (common structures) into OC objects so that they can be put into OC arrays and dictionaries.

Cgpoint p = cgpointmake (10, 10); nsvalue* v = [nsvalue valuewithpoint:p]cgpoint pt = [v Pointvalue];

2 NSNumber
The underlying data type (number) is loaded into an object so that it can be put into the OC array and the dictionary.

NSNumber NUM1 = [NSNumber numberwithint:10]; NSNumber num2 = [NSNumber numberwithlong:10]; NSNumber num3 = [NSNumber numberwithbool:true]; NSNumber num4 = [NSNumber numberwithfloat:10.0]; NSNumber num4 = @10;//quick Convert int count = 5; NSNumber NUM5 = @ (count), ... int i = [NUM1 intvalue];int l = [num1 longvalue];int b = [num1 boolvalue];int f = [Num1 floatv Alue];..

Four nsdate dates

<pre name= "code" class= "OBJC" >nsdate* d1 = [NSDate date];//return current time NSLog (@ "%@", D1)//GMT time (0 o'clock area), with Beijing (East eight district) Time difference 8 hours nsdate* d2 = [nsdate datewithtimeinterval:5 sincedate:d1];//interval nstimeinterval sec1 = [D2 timeIntervalSince1970] ; Nstimeinterval sec2 = [D2 timeintervalsincenow];//date formatting nsdateformatter* f1 = [[NSDateFormatter alloc]init];//y year M-month D-Day H ( 12-hour system) H (24-hour system) m min s s f1.dateformat = @ "Yyyy-mm-dd HH:mm:ss"; nsstring* datestr = [F1 stringfromdate:d1]; nsstring* timestr = @ "2015/02/04 16:57"; nsdateformatter* F2 = [[NSDateFormatter Alloc]init];f2.dateformat = @ "Yyyy/mm/dd hh:mm"; nsdate* d3 = [F2 datefromstring:timestr];

iOS Review Note 14: Common data structures and the like