OC string NSString, ocnsstring

OC string NSString, ocnsstring

======================================

Advanced object-oriented programming and strings

======================================

△1. Design Pattern of the Class-singleton

[Singleton] only one piece of memory space exists in a program. This type of design mode becomes Singleton.

[Q] When to use the Singleton?

[Answer] when data is shared

 

1. Writing format of the singleton

Methods Starting with + (plus sign) can be directly called by classes; Methods Starting with-(minus sign) are object methods that are called by objects;

 

2. Recognition Singleton

[See singleDemo]

 

[Note] The Name Of The Singleton method can be used at will, but it is recommended that the method be well known!

 

 

Exercise 1: Create a singleton class single with a typeid attribute. Create a dog class and a cat class;

Requirements: The dog class is responsible for modifying the attribute value of the single class, and cat is responsible for extracting the typeid value.

[Thinking] How can we achieve this without a Singleton?

 

2. get and set methods and. Attributes

 

Exercise 2: Create a cat class and implement the get and set methods in the Code. The cat class contains the speed member variable.

Requirement: the first method is get and set.

Method 2: @ property

Exercise 3: You must use @ property to modify the question in Exercise 1.

 

================================

String

================================

 

1. Recognize the strings in oc

In oc, the content contained in @ "" is a string, regardless of the length of the string contained in.

[Example]: @ "a", @ "123", @ "_ % ^ &*",

[Note] "" is used for strings in C language and @ "" is used in oc.

 

NSString

[See strDemo1]

 

// Declare a string of NSString type

// NSString is the type of A Class. Its usage is the same as that of the basic type.

// NSString is a string class encapsulated by Apple.

// Defines the str object variable and assigns the initial value @ "hello world! "

NSString * str = @ "hello world! ";

// C string

// Char a [64] = "hello ";

// A [0], a [1]...

// NSString * str1 = [[NSString alloc] initWithFormat: @ "% @", str];

// NSLog (@ "% @", str1 );

// Evaluate the string length --- length

// Common int type in oc, not common in NSUInteger

NSUInteger length = [str length];

NSLog (@ "% ld", length );

// Complete String concatenation

NSString * Str1 = @ "yudejun ";

NSString * Str2 = @ "xijinping ";

// The string format conversion character in oc is: % @

// When the compiler encounters a formatted conversion character, it will automatically replace it with the variable value corresponding to the following parameter.

NSString * Str3 = [NSString stringWithFormat: @ "% @ and % @", Str1, Str2];

NSLog (@ "% @", Str3 );

// [Exercise]

// Splice two strings. The content of the first string is @ "hello", and the second string is @ "China". Print the length after splicing.

NSString * str4 = @ "hello ";

NSString * str5 = @ "China ";

NSString * str6 = [NSString stringWithFormat: @ "% @", str4, str5];

NSString * str6 = [NSString stringWithFormat: @ "% d", 324123];

NSLog (@ "% ld", [str6 length]);

// String Conversion

NSString * StrInt = @" 123456789987654321 ";

Int a = [StrInt intValue];

NSLog (@ "% d", );

Long B = [StrInt longLongValue];

// @ "0.1234"

// NSString * StrFloat = @" 0.1234 ";

Float c = [@ "0.1234" floatValue];

// Exercise: calculate the value of @ "1234" @ "0.25" @ "199" @ "0.5" and print it out.

// String segmentation

// [Note] string segmentation must be within the Valid String Length range.

NSString * tempStr = @ "helloworld ";

// NSString * FStr = [tempStr substringFromIndex: 5];

// NSString * FStr = [tempStr substringToIndex: 5];

Nsange range = {2, 3 };

NSString * FStr = [tempStr substringWithRange: range];

 

NSLog (@ "% @", FStr );

// String comparison

NSString * tem1 = @ "abc ";

NSString * tem2 = @ "abc ";

// Determine whether tem1 is equal to tem2

If ([tem1 is1_tostring: tem2]) {

NSLog (@ "equal ");

}

Else

{

NSLog (@ "not equal ");

}

NSComparisonResult result = [tem1 compare: tem2];

If (result = NSOrderedAscending ){

NSLog (@ "tem2> tem1 ");

}

Else if (result = NSOrderedDescending)

{

NSLog (@ "tem2 <tem1 ");

} Else if (result = NSOrderedSame)

{

NSLog (@ "tm2 = tem1 ");

}

// BOOL is a boolean type. There are only two statuses: true or false. You can use 1, 0, yes, or no.

// Determine the string prefix and suffix

NSString * string = @ "http://www.baidu.com ";

BOOL have = [string hasPrefix: @ "http: //"];

If (have = YES ){

NSLog (@ "starting with http ");

}

Else

{

NSLog (@ "not starting with http ");

}

BOOL havejiewei = [string hasSuffix: @ "com"];

If (havejiewei ){

NSLog (@ "end with com ");

}

Else

{

NSLog (@ "not the end of com ");

}

// Convert to uppercase

NSLog (@ "% @", [string uppercaseString]);

// Convert to lowercase

[String lowercaseString];

// Uppercase letters of all words

[String capitalizedString];

// Search for a string and replace it. The first parameter is the string to be searched, and the second string is the string to be replaced.

String = [string stringByReplacingOccurrencesOfString: @ "www" withString: @ "googl"];

NSLog (@ "% @", string );

NSString * tmp = @ "ceshishuju ";

// ================================================ ===

NSMutableString * m_str = [[NSMutableString alloc] initWithString: tmp];

// Modify the string

[M_str setString: @ "hello world"];

// Append the string

[M_str appendFormat: @ "nihao"];

// Delete a string

Nsange rang = {1, 2 };

[M_str deleteCharactersInRange: rang];

// String insertion

[M_str insertString: @ "xijinping" atIndex: 3];

NSLog (@ "% @", m_str );

// All objects starting with NSMutable can be of variable type, and objects starting with NSMutable can be modified;

// NSString // immutable string

// NSMutableString // variable string

// NSArray // unchangeable Array

// NSMutableArray // variable array

// NSDictionary // unchangeable dictionary

// NSMutableDictionary // variable dictionary

// Variable means that the variables defined for this type can be modified or deleted.