Introduction to the usage of NSNumber and nsdictionary in Objective-c _ios

Common methods of NSNumber

Why use a numeric object NSNumber when you have a data type for int in objective-c? This is because many classes, such as Nsarray, require the use of objects, and int is not an object.
NSNumber is a digital object we can use the NSNumber object to create and initialize different types of numeric objects.
NSNumber
+ (NSNumber *) Numberwithint: (int) value;
+ (NSNumber *) Numberwithdouble: (double) value;
-(int) intvalue;
-(double) doublevalue;
..................... (For each base type, the class method assigns a NSNumber object to it and sets it to the specified value, which starts with Numberwith, followed by the type, such as Numberwithfloat,numberwithlong, Numberwithinteger ...)
After packing, the following methods are taken:

Here, take int for a demo:

Copy Code code as follows:

void Number () {
Wrapping 10 of int type into a NSNumber object
NSNumber *number = [NSNumber numberwithint:10];
NSLog (@ "number=%@", number);

Nsmutablearray *array = [Nsmutablearray array];
Add values to an array
[Array Addobject:number];

Removed or a NSNumber object, does not support automatic unpack (that is, not automatically converted to int type)
NSNumber *number1 = [array lastobject];

Convert NSNumber to int type
int num = [Number1 intvalue];
NSLog (@ "num=%i", num);
}

Nsdictionary some common usage

Copy Code code as follows:

Nsarray * skyaarrays = [Nsarray arraywithobjects:@ "a Sky No. 1th", @ "a Sky 2nd", @ "a Sky 3rd", Nil];
Nsarray * skybarrays = [Nsarray arraywithobjects:@ "B Sky No. 1th", @ "B Sky 2nd", @ "B Sky 3rd", Nil];
Nsarray * skycarrays = [Nsarray arraywithobjects:@ "C Sky No. 1th", @ "C Sky 2nd", @ "C Sky 3rd", Nil];

Nsarray * Skyarray = [Nsarray arraywithobjects:skyaarrays,skybarrays,skycarrays, Nil];

All key in the dictionary
Nsarray * keys = [Nsarray arraywithobjects:@ "name", @ "sex", @ "age", nil];
All the value in the dictionary corresponding to the key
Nsarray * values = [Nsarray arraywithobjects:@ "Liuhui", @ "male", [Nsnumbernumberwithint:36],nil];
Create a Dictionary object Method 1
Nsdictionary * Mydic = [[Nsdictionary alloc]initwithobjects:values Forkeys:keys];
NSLog (@ "My dic =%@", mydic);
Create a Dictionary object Method 2
Nsdictionary * Yourdic = [[Nsdictionary alloc] initwithobjectsandkeys:skyaarrays,@ "A", skybarrays,@ "B", skyCArrays,@ "C" ", nil];
NSLog (@ "Your dic =%@", yourdic);

NSLog (@ "%@", [Yourdic objectforkey:@ "A"]);
-(Nsarray *) AllKeys; Return is the Nsarray type, easy to use Objectatindex to remove a key
NSLog (@ "%@", [Yourdic AllKeys]);
NSLog (@ "%@", [Yourdic allvalues]);

Add data (SetObject generally do not have a key to add, with the same name of the key and in this way, will be overwritten), Note: ID key appears in pairs
[Mutabledictionary setobject:@ "Good lucky" forkey:@ "why"];
[Mutabledictionary setobject:@ "Bye Bye" forkey:@ "how"];

Delete the data for the specified key value
[Mutabledictionary removeobjectforkey: ...];
Delete all data
[Mutabledictionary removeallobjects];

Common traversal of dictionaries (unordered)
for (int i =0 i < [yourdic count]; i++) {
NSLog (@ "key = value <====>%@ =%@" "[[Yourdic AllKeys] objectatindex:i],[yourdic objectforkey:[[yourdic AllKeys] OBJECTATINDEX:I]]);
}

Fast traversal of the dictionary fetched out obj must be key
for (id obj in yourdic) {
NSLog (@ "%@", obj);
ID value = [yourdic objectforkey:obj];
NSLog (@ "%@", value);
}