Sort of Nsarray
Copy Code code as follows:
+ (ID) studentwithfirstname: (NSString *) firstName lastName: (NSString *) lastname{
Student *stu = [[Student alloc] init];
Stu.firstname = FirstName;
Stu.lastname = LastName;
return Stu;
}
+ (ID) studentwithfirstname: (NSString *) firstName lastName: (NSString *) lastName bookname: (NSString *) bookname{
Student *stu = [Student studentwithfirstname:firstname lastname:lastname];
Stu.book = [book Bookwithname:bookname];
return Stu;
}
-(Nscomparisonresult) Comparestudent: (Student *) stu{
Nscomparisonresult result = [Self.firstname compare:stu.firstName];
if (result = = Nsorderedsame) {
result = [Self.lastname compare:stu.lastName];
}
return result;
}
-(NSString *) description{
return [NSString stringwithformat:@ "%@%@%@", Self.firstname,self.lastname,self.book.name];
return [NSString stringwithformat:@ "%@%@%@", Self.firstname,self.lastname,_book.name];
}
#pragma mark 3.NSArray Sort 1
void ArraySort1 () {
Nsarray *array = [Nsarray arraywithobjects:@ "2", @ "3", @ "1", @ "4", nil Nil];
A comparison method for specifying the system's own rules compare:
Nsarray *array2 = [Array sortedarrayusingselector: @selector (compare:)];
NSLog (@ "%@", array2);
}
#pragma mark 3.NSArray Sort 2
void ArraySort2 () {
Student *STU1 = [Student studentwithfirstname:@ "Hu" lastname:@ "Mingtao"];
Student *STU2 = [Student studentwithfirstname:@ "Zhu" lastname:@ "Wenpeng"];
Student *STU3 = [Student studentwithfirstname:@ "Zhao" lastname:@ "Weisong"];
Student *stu4 = [Student studentwithfirstname:@ "Hu" lastname:@ "Junpeng"];
Nsarray *array = [Nsarray arraywithobjects:stu1,stu2,stu3,stu4, nil Nil];
Like CompareTo in Java, you define the comparison, but you must implement the Compare method
Nsarray *array2 = [Array sortedarrayusingselector: @selector (comparestudent:)];
NSLog (@ "%@", array2);
}
#pragma mark 3.NSArray sort 3-block Sorting
void ArraySort3 () {
Student *STU1 = [Student studentwithfirstname:@ "Hu" lastname:@ "Mingtao"];
Student *STU2 = [Student studentwithfirstname:@ "Zhu" lastname:@ "Wenpeng"];
Student *STU3 = [Student studentwithfirstname:@ "Zhao" lastname:@ "Weisong"];
Student *stu4 = [Student studentwithfirstname:@ "Hu" lastname:@ "Junpeng"];
Nsarray *array = [Nsarray arraywithobjects:stu1,stu2,stu3,stu4, nil Nil];
Nsarray *array2 = [Array Sortedarrayusingcomparator:^nscomparisonresult (Student *obj1, Student *obj2) {
Nscomparisonresult result = [Obj1.firstname compare:obj2.firstName];
if (result = = Nsorderedsame) {
result = [Obj1.lastname compare:obj2.lastName];
}
return result;
}];
NSLog (@ "%@", array2);
}
#pragma mark 4.NSArray Sort 4-advanced sort
void ArraySort4 () {
Student *STU1 = [Student studentwithfirstname:@ "Hu" lastname:@ "Mingtao" bookname:@ "Lianai"];
Student *STU2 = [Student studentwithfirstname:@ "Zhu" lastname:@ "Wenpeng" bookname:@ "Tianshi"];
Student *STU3 = [Student studentwithfirstname:@ "Zhao" lastname:@ "Weisong" bookname:@ "Love"];
Student *stu4 = [Student studentwithfirstname:@ "Hu" lastname:@ "Junpeng" bookname:@ "Qingren"];
Nsarray *array = [Nsarray arraywithobjects:stu1,stu2,stu3,stu4, nil Nil];
1. First sort by title
Nssortdescriptor *booknamedesc = [Nssortdescriptor sortdescriptorwithkey:@ "Book.name" Ascending:YES];
2. Sort by last name first
Nssortdescriptor *firstnamedesc = [Nssortdescriptor sortdescriptorwithkey:@ "FirstName" ascending:yes];
3. Sort by First Name
Nssortdescriptor *lastnamedesc = [Nssortdescriptor sortdescriptorwithkey:@ "LastName" ascending:yes];
Nsarray *array2 = [Array Sortedarrayusingdescriptors:[nsarray arraywithobjects:booknamedesc,firstnamedesc, Lastnamedesc, nil Nil]];
NSLog (@ "%@", array2);
}
some usages of Nsarray
Nsarray only allows OC objects, and cannot load null values, empty represents the end of an array element
Copy Code code as follows:
Basic usage of #pragma mark-nsarray
Create an empty array
Nsarray *array = [Nsarray array];
To create an array with an element
Array = [Nsarray arraywithobject:@ "123"];
To create an array with multiple elements
Array = [Nsarray arraywithobjects:@ "a", @ "B", nil];//cannot install nil null pointer, null value represents end of array element
Assigns an array to an array
+ (Instancetype) Arraywitharray: (Nsarray *) array;
Get the number of elements
int count = [array count]; and count = Array.count; The same is called the Get method
Whether to include an element
-(BOOL) Containsobject: (ID) anobject;
Returns the last element
-(ID) lastobject;
Gets the element of the index position
-(ID) Objectatindex: (Nsuinteger) index;
Get the location of the element
-(Nsuinteger) Indexofobject: (ID) anobject;
Find the location of an element in range range
-(Nsuinteger) Indexofobject: (ID) anobject inrange: (nsrange) range;
Compare two collection contents to be identical
-(Bool) Isequaltoarray: (Nsarray *) Otherarray;
Returns the first identical object element in a two collection
-(ID) Firstobjectcommonwitharray: (Nsarray *) Otherarray;
Advanced usage of #pragma mark-nsarray
So that all the elements in the collection are executed Aselector this method
-(void) Makeobjectsperformselector: (SEL) Aselector;
Let all elements in the collection execute Aselector this method, add parameters to this method, but only one argument is supported
-(void) Makeobjectsperformselector: (SEL) Aselector withobject: (ID) argument
Adds an element that returns a new Nsarray (the method caller itself has not changed)
-(Nsarray *) Arraybyaddingobject: (ID) anobject
Adds all the elements of the Otherarray, returns a new Nsarray (method does not change itself)
-(Nsarray *) Arraybyaddingobjectsfromarray: (Nsarray *) Otherarray;
To intercept an array of range ranges
-(Nsarray *) Subarraywithrange: (nsrenge) range;
Use separator as a concatenation character, stitching into a string
-(NSString *) componentsjoinedbystring: (NSString *) separator
Persisting Nsarray to a file
-(BOOL) WriteToFile: (NSString *) path atomically: (BOOL) Useauxiliaryfile
#pragma mark-nsarray traversal
//Method One: Normal traversal (using for loop)
void ArrayFor1 () {
nsarray *array = [Nsarray arraywithobjects:@ 1 ", @" 2 ", @" 3 ", nil];
int count = Array.count;
for (int i=0; i<count; i++) {
id obj = [array objectatindex:i];
NSLog (@ "%i-%@", I, obj);
}
}
/Method Two: Fast traversal
void ArrayFor2 () {
Nsarray *array = [Nsarray arraywithobjects:@ "1", @ "2", @ "3", nil];
int count = Array.count;
int i=0;
for (id obj in array) {
NSLog (@ "%i-%@", I, obj);
i++;
}
}
//Method Three: Using block traversal
void ArrayFor3 () {
Nsarray * Array = [Nsarray arraywithobjects:@ "1", @ "2", @ "3", nil];
[Array enumerateobjectsusingblock:^ (id obj, Nsuinteger idx, BOOL *stop) {
NSLog (@ "%zi->%@", IDX, obj);
// *stop = YES; Change the outer bool, terminate the traversal
}];
}
Method Four: Using the iterator
To introduce the-->nsenumerator iterator: The iterator of the collection, which can be used to traverse the collection elements, Nsarray have the appropriate method to get the iterator
Gets the iterator of a positive sequence traversal
-(Nsenumerator *) Objectenumerator;
Gets an iterator for reverse-sequence traversal
-(Nsenumerator *) Reverseobjectenumerator;
@ Common methods:
Get Next element
-(ID) nextobject;
Get all the Elements
-(Nsarray *) allobjects
void ArrayFor4 () {
Nsarray *array = [Nsarray arraywithobjects:@ "1", @ "2", @ "3", nil];
Nsenumerator *enumerator = [Array objectenumerator];//returns an iterator for an array
If you put it after the traversal, you get empty, because, after the traversal, there is no value.
Nsarray *array2 = [enumerator allobjects];
NSLog (@ "array2=%@", array2);
Gets the next element that needs to be traversed
ID obj = nil;
while (obj = [Enumerator nextobject]) {
NSLog (@ "obj=%@", obj);
}
}
Use block blocks to traverse the entire array. This block requires three parameters, and ID obj represents the elements in the array.
Nsuinteger idx The subscript of the element,
Boolbool *stop is an argument of type bool. The official description is as follows:
A reference to a Boolean value. The block can set the value to YES to stop further processing of the array.
The Stop argument is a out-only argument. You should only ever set this Boolean to YES within.
-(void) Enumerateobjectsusingblock: (void (^) (id obj, Nsuinteger idx,boolbool *stop) block
Call examples such as:
Copy Code code as follows:
Nsarray *array = [Nsarray arraywithobjects:@ "Wendy", @ "Andy", @ "Tom", @ "test", nil Nil];
[Array enumerateobjectsusingblock:^ (ID str,nsuinteger index, bool* te) {
NSLog (@ "%@,%d", Str,index);
}];
As with the above method, the difference is that a parameter is added here to indicate whether it is traversing backwards or forwards.
-(void) Enumerateobjectswithoptions: (nsenumerationoptions) opts Usingblock: (void (^) (id obj, nsuinteger idx,boolbool * Stop)) block
The invocation example is as follows:
Copy Code code as follows:
Nsarray *array = [Nsarray arraywithobjects:@ "Wendy", @ "Andy", @ "Tom", @ "test", nil Nil];
[Array enumerateobjectswithoptions:nsenumerationreverse usingblock:^ (ID str,nsuinteger index, bool* te) {
NSLog (@ "%@,%d", Str,index);
}];
