ObjectC ---- several common classes

ObjectC ---- several common classes

// Create By Guo Zai March 31, 2015 20:54:20

1. NSString class

 

 

// Evaluate the string length

NSString * str = @ "Hello Guo String ";

NSUInteger len = [str length]; // NSUInterger is long

NSLog (@ "% ld", len );

 

// Obtain the substring

 

 

NSString * substr = [str substringFromIndex: 5]; // obtain the substring starting from subscript 5

NSLog (@ "% @", substr );

// The End Of The substring from the start to the position where the subscript is 5

NSString * substr2 = [str substringToIndex: 5];

NSLog (@ "% @", substr2 );

 

Nsange rang = {2, 3}; // start position and length

// Obtain the substring of 3 from the starting position 2

NSString * substr3 = [str substringWithRange: rang];

NSLog (@ "% @", substr3 );

 

// Concatenate a string

 

NSString * comStr1 = [str stringByAppendingString: @ "IOS"];

NSLog (@ "% @", comStr1 );

 

NSString * comStr2 = [str stringByAppendingFormat: @ "hehe % @", @ "hhh", @ "jjj"];

NSLog (@ "% @", comStr2 );

 

 

// String replacement

 

NSString * newStr1 = [str stringByReplacingOccurrencesOfString: @ "string" withString: @ "world"];

NSLog (@ "% @", newStr1 );

 

 

// Judge whether the string is equal

// Use the iseconto method to determine whether the string is equal. The = method cannot be used to determine whether the string is equal.

// Whether the content of the string is equal when the issimilar to method is used, and = whether the two pointers point to the same address

 

NSString * cmpStr = @ "Hello String ";

BOOL eq = [str isw.tostring: cmpStr];

If (eq ){

NSLog (@ "equal ");

}

Else {

NSLog (@ "not equal ");

}

// Determine whether the prefix is equal to the given string, that is, whether the string starts

BOOL prefix = [str hasPrefix: @ "Hello"];

If (prefix ){

NSLog (@ "starting with Hello ");

}

Else {

NSLog (@ "not starting with Hello ");

}

 

 

 

// Determine the suffix

// Determine whether the image has ended with png. If it is png, replace it with jpg. Otherwise, splice the image with jpg.

BOOL isPng = [str hasSuffix: @ "png"];

If (isPng ){

// Execute replacement

NSString * tem = [str stringByReplacingOccurrencesOfString: @ "png" withString: @ "jpg"];

NSLog (@ "% @", tem );

}

Else

{// Execute the mosaic jpg

NSString * tem = [str stringByAppendingString: @ "jpg"];

NSLog (@ "% @", tem );

}

 

 

 

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

2. NSMutableString // variable string

NSMutableString * mulStr = [NSMutableString stringWithString: @ "Hello"];

NSLog (@ "% @", mulStr );

 

// Splicing

[MulStr appendFormat: @ "guozai"];

NSLog (@ "% @", mulStr );

[MulStr appendString: @ "mutible"];

NSLog (@ "% @", mulStr );

 

 

// Delete the substring

Nsange ran = {4, 1}; // struct type

[MulStr deleteCharactersInRange: ran];

NSLog (@ "% @", mulStr );

 

// Replace

Nsange ran2 = {3, 2 };

[MulStr replaceCharactersInRange: ran2 withString: @ "yy"];

NSLog (@ "% @", mulStr );

 

// Insert

[MulStr insertString: @ "tt" atIndex: 2];

NSLog (@ "% @", mulStr );

 

 

// A new string is created for String concatenation, segmentation, and other operations of an immutable string NSString.

// For variable string NSMutableString, such as String concatenation, segmentation, replacement, and other operations are based on the original string

// Modify the string. No new string is created.

// NSMutableString is a subclass of NSString. Therefore, the NSMutableString method is also

// Available

// In the future study, any Mutable class will not have a subclass of the Mutable class:

// For example, NSMutableArray is a subclass of NSArray and NSMutableDictionary is a child of NSDictonary

// Class

========================================================== ========================================================== ==== 3. NSArray

 

// Array

// The final nil cannot be lost

NSArray * arr = [NSArray arrayWithObjects: @ "guozai", @ "guo", @ "zaiguo", nil];

 

// Obtain the number of array elements

NSUInteger count = [arr count];

NSLog (@ "% lu", count );

 

 

// Obtain the first object

NSString * p1 = [arr firstObject];

NSLog (@ "% @", p1 );

 

 

// Obtain the last object

NSString * p2 = [arr lastObject];

NSLog (@ "% @", p2 );

 

// Obtain the object corresponding to the subscript

NSString * p3 = [arr objectAtIndex: 1];

NSLog (@ "% @", p3 );

 

 

// Traverse the Array

For (int I = 0; I <[arr count]; I ++ ){

NSLog (@ "% @", [arr objectAtIndex: I]);

}

========================================================== ========================================================== ===== 4. NSMutableArray

 

// Variable array

// The content of one array is assigned to another array.

NSMutableArray * mulArray = [NSMutableArray arrayWithArray: arr];

// Delete the object whose subscript is index

[MulArray removeObjectAtIndex: 2];

 

// For (int I = 0; I <[arr count]; I ++ ){

// NSLog (@ "% @", [arr objectAtIndex: I]);

//}

//

// Add an object element

[MulArray addObject: @ "guoguo"];

 

// Exchange element objects corresponding to subscript

[MulArray exchangeObjectAtIndex: 0 withObjectAtIndex: [mulArray count]-1]; // swap the first and last elements

========================================================== ========================================================== ===== See the following example: you can use a variable array to manage the BOOk class. to add, delete, query, and modify a BOOK, there are two member variables: _ name, _ price;

Book * book1 = [[Book alloc] initWithName: @ "guozai1" andPrice: 10];

Book * book2 = [[Book alloc] initWithName: @ "guozai2" andPrice: 15];

Book * book3 = [[Book alloc] initWithName: @ "guozai3" andPrice: 13];

 

// Array assignment

NSMutableArray * books = [NSMutableArray arrayWithObjects: book1, book2, book3, nil];

 

Book * book4 = [[Book alloc] initWithName: @ "guozai4" andPrice: 12];

 

// Add a book

[Books addObject: book4];

 

// Delete a book

[Books removeObjectAtIndex: 2];

 

For (int I = 0; I <[books count]; I ++ ){

NSLog (@ "% @, %. 2f", [[books objectAtIndex: I] name], [[books objectAtIndex: I] price]);

}

 

 

// Find the book named guozai3 and print the price

For (int I = 0; I <[books count]; I ++ ){

If ([[books objectAtIndex: I] name] isw.tostring: @ "guozai3"]) {

NSLog (@ "% f", [[books objectAtIndex: I] price]);

}

}

 

// Sort the array by price from high to low

For (int I = 0; I <[books count]-1; I ++ ){

For (int j = 0; j <[books count]-I-1; j ++ ){

If ([books [j] price] <[books [j + 1] price]) {

[Books exchangeObjectAtIndex: j withObjectAtIndex: j + 1];

}

}

}

 

 

For (int I = 0; I <[books count]; I ++ ){

NSLog (@ "% @, %. 2f", [books [I] name], [books [I] price]);

}

========================================================== ========================================================== ========= 5. NSNumber: converts a basic data type to an object type.

// Convert the basic data type int to the object type

NSNumber * intNum = [NSNumber numberWithInt: 100]; // Constructor

NSMutableArray * ar = [NSMutableArray arrayWithObjects: intNum, nil];

NSNumber * tem = [ar objectAtIndex: 0];

 

// Convert the object type to the basic data type

Int result = [tem intValue];

NSLog (@ "% d", result );

========================================================== ========================================================== ========= 6. NSValue: converts struct into objects

// Convert a vertex into an NSValue object

NSPoint point = {1, 2 };

// Convert a struct into an NSValue object

NSValue * vPoint = [NSValue valueWithPoint: point];

 

// Convert a vPoint into a struct

NSPoint point2 = [vPoint pointValue];

// NSLog (@ "%. 2f, %. 2f", point2.x, point2.y );

 

// NSStringFromPoint can convert a vertex into a string

NSLog (@ "% @", NSStringFromPoint (point2 ));

The analogy of other examples is as follows:

 

// Convert the NSsize struct into an NSValue object

NSSize size = {22, 44 };

NSValue * sValue = [NSValue valueWithSize: size];

 

// Convert the NSValue object into an NSSize struct;

NSSize size2 = [sValue sizeValue];

NSLog (@ "% @", NSStringFromSize (size2 ));

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