NSPredicate predicate usage in IOS development, iosnspredicate Predicate

NSPredicate predicate usage in IOS development, iosnspredicate Predicate

Programmers should have some knowledge about SQL statements, whether they have been in college or from training institutions, back-end or front-end. We know that, in SQL statements, where condition expressions can filter data in two-dimensional Relational Tables. microsoft C #. net also implements a technology that can rival SQL statements. It is a Lambda expression of a List generic set and supports searching, sorting, comparison, and combination. although java does not integrate the implementation of List object operations in languages, third-party open-source libraries also implement this function. A powerful NSPredicate class is provided in the Cocoa framework for IOS development. Here we will discuss where it is powerful...
NSPredicate inherits from NSObject and has two derived subclasses.
• NSComparisonPredicate
• NSCompoundPredicate)
Speaking of predicates, Let's first look at the syntax of the predicates.
1. Comparison Operators
*>: Greater
* <: Less
* >=: Greater than or equal
* <=: Less than or equal
* =, =: Equal
*! =, <>: Not equal

2. logical operators
* And/& and
* Or/| or
* Not /! Non
3. Relational operators
* ANY, SOME
* ALL elements
* NONE no element is equivalent to not any
* In inclusion
4. Range Operators
* Between, for example, 1 BETWEEN {0, 33}, or $ input between {$ LOWER, $ UPPER }.
* In inclusion

4. string itself
* SELF, for example, @ "self = 'appleios '"
5. String-related
* Contain
*
* Endswith
6. like wildcard
* Like: @ "name like [cd] '* ios *'"
@ "Name" like [cd] 'ios *'"
7. Regular Expression matches
* For example, NSString * regex = @ "^ A. + e $"; // starts with A and ends with e.
@ "Name MATCHES % @", regex
8. Array Operations
* Array [index]: Specifies the element at a specific index in the array.
* Array [first]: Specify the first element.
* Array [last]: Specifies the last element.
* Array [size]: Specifies the array size.
Let's take a look at the specific example below:

Create a project, and then add the products class

Products.h

1 // 2 // Products. h 3 // NSPredicateTest 4 // 5 // Created by xuhongjiang on 15/10/27. 6 // Copyright (c) 2015 xuhongjiang. all rights reserved. 7 // 8 9 # import <Foundation/Foundation. h> 10 11 @ interface Products: NSObject12 @ property NSString * productName; 13 @ property NSInteger productCount; 14 @ property NSString * productImageUrl; 15 + (id) initProductWithName :( NSString *) name withCount :( NSInteger) count withImage :( NSString *) imageurl; 16 @ end

Products.m

1 // 2 // Products. m 3 // NSPredicateTest 4 // 5 // Created by xuhongjiang on 15/10/27. 6 // Copyright (c) 2015 xuhongjiang. all rights reserved. 7 // 8 9 # import "Products. h "10 11 @ implementation Products12 + (id) initProductWithName :( NSString *) name withCount :( NSInteger) count withImage :( NSString *) imageurl13 {14 Products * sprducts = [[Products alloc] init]; 15 sprducts. productName = name; 16 sprducts. productCount = count; 17 sprducts. productImageUrl = imageurl; 18 return sprducts; 19} 20-(NSString *) description21 {22 NSString * str = [NSString stringWithFormat: @ "Product Name: % @, quantity: % ld, figure: % @ ", _ productName, _ productCount, _ productImageUrl]; 23 return str; 24} 25 @ end

Test method:

1 // 2 // ViewController. m 3 // NSPredicateTest 4 // 5 // Created by xuhongjiang on 15/10/27. 6 // Copyright (c) 2015 xuhongjiang. all rights reserved. 7 // 8 9 # import "ViewController. h "10 # import" Products. h "11 12 @ interface ViewController () 13 14 @ end 15 16 @ implementation ViewController 17 18-(void) viewDidLoad {19 [super viewDidLoad]; 20 [self mainTest]; 21} 22 23-(void) didReceiveMemo RyWarning {24 [super didReceiveMemoryWarning]; 25} 26 27-(void) mainTest 28 {29 Products * p1 = [Products initProductWithName: @ "A apple sdasf" withCount: 2 withImage: @ "464.jpg"]; 30 Products * p2 = [Products initProductWithName: @" fsdf orange gag "withCount: 53 withImage: @" fsdfas.jpg "]; 31 Products * p3 = [Products initProductWithName: @ "dfgdf banana" withCount: 5 withImage: @ "sfas.jpg"]; 32 Products * p4 = [Products initProdu CtWithName: @ "Samsung" withCount: 76 withImage: @ "ggas.jpg"]; 33 Products * p5 = [Products initProductWithName: @ "Huawei dfsd" withCount: 9 withImage: @ "gasa.jpg"]; 34 Products * p6 = [Products initProductWithName: @ "dhdhdhnnne" withCount: 6 withImage: @ "hshhh.jpg"]; 35 Products * p7 = [Products initProductWithName: @ "Samsung" withCount: 6 withImage: @ "hshhh.jpg"]; 36 Products * p8 = [Products initProductWithName: @ "15300250500" withCount: 6 withImage: @ "hshhh.jpg"]; 37 38 NSArray * sproducts = [NSArray arrayWithObjects: p1, p2, p3, p4, p5, p6, p7, nil]; 39 40 // number less than 9 define the predicate containing the filter condition 41 NSPredicate * prdicate = [NSPredicate predicateWithFormat: @ "productCount <% d", 9]; 42 // The filter result returns a new array 43 NSArray * newArray = [sproducts filteredArrayUsingPredicate: prdicate]; 44 for (Products * item in newArray) {45 NSLog (@ "newArray = % @", item. productName); 46} 47 48 49 // large quantity In 9 and productname is equal to the "Samsung jfggg" definition predicateWithFormat: @ "productName = 'samsung '& amp; productCount> 9"]; 51 // The filter result returns the new array 52 newArray = [sproducts filteredArrayUsingPredicate: prdicate]; 53 for (Products * item in newArray) {54 NSLog (@ "newArray =% @", item. productName); 55} 56 57 // in (inclusive) * Note that the inclusion is full-character match 58 prdicate = [NSPredicate predicateWithFormat: @ "productName IN {'G', 'huawei ', 'samsung '} | pro DuctCount IN {} "]; 59 // The filter result returns the new array 60 newArray = [sproducts filteredArrayUsingPredicate: prdicate]; 61 for (Products * item in newArray) {62 NSLog (@ "newArray = % @", item. productName); 63} 64 65 66 // productName 67 prdicate = [NSPredicate predicateWithFormat: @ "productName BEGINSWITH 'A'"] starting with a; 68 // productName end with ba 69 prdicate = [NSPredicate predicateWithFormat: @ "productName ENDSWITH 'G'"]; 70 71/ /Name 72 prdicate = [NSPredicate predicateWithFormat: @ "productName CONTAINS 'A'"]; 73 74 // like match any number of characters 75 // productName must have s characters and the conditions are met. 76 prdicate = [NSPredicate predicateWithFormat: @ "productName like's * '"]; 77 //? Represents a character. The following query condition is: The second character in name is s's 78 prdicate = [NSPredicate predicateWithFormat: @ "productName like '? S * '"]; 79 80 newArray = [sproducts filteredArrayUsingPredicate: prdicate]; 81 for (Products * item in newArray) {82 NSLog (@" newArray = % @ ", item. productName); 83} 84 85 // regular expression to verify whether the mobile phone number is 86 BOOL isMobileNum = [self isMobileNumber: p8.productName]; 87 if (isMobileNum) 88 NSLog (@ "is a real mobile phone number: % @ ", p8.productName); 89 90} 91 92 93-(BOOL) isMobileNumber :( NSString *) mobileNum 94 {95/** 96 * mobile phone number 97: 134 [0-8], 135,136,137,138,139,150,151,157,158,159,182,187,188 98 * China Unicom: 130,131,132,152,155,156,185,186 99 * China Telecom: 133,1349, 153,180,189 101 */NSString * MOBILE = @ "^ 1 (3 [0-9] | 5 [0-35-9] | 8 [025-9]) \ d {8} $ "; 102/** 103 10 * China Mobile: China Mobile104 11*134 [0-8], 135,136,137,138,139,150,151,157,158,159,182,187,188 105 12 */106 NSString * CM = @ "^ 1 (34 [0-8] | (3 [5-9] | 5 [017-9] | 8 [278 ]) \ d) \ d {7} $ "; 107/** 108 15 * China Unicom: china Unicom109 16*130,131,132,152,155,156,185,186 110 17 */111 NSString * CU = @ "^ 1 (3 [0-2] | 5 [256] | 8 [56]) \ d {8} $ "; 112/** 113 20 * China Telecom: China Telecom114 21*133,1349, 153,180,189 116 22 */349 NSString * CT = @ "^ 1 (33 | 53 | 8 [09]) [0-9] |) \ d {7} $ "; 117/** 118 25 * fixed line telephone and PHS 119 26 * area code: 010,020,021,022,023,024,025,027,028,029 120 27 * Number: seven or eight digits 121 28 */122 // NSString * PHS = @ "^ 0 (10 | 2 [0-5789] | \ d {3 }) \ d {123} $ "; 124 125 NSPredicate * regextestmobile = [NSPredicate predicateWithFormat: @" self matches % @ ", MOBILE]; NSPredicate * regextestcm = [NSPredicate response: @ "self matches % @", CM]; 126 NSPredicate * regextestcu = [NSPredicate primary: @ "self matches % @", CU]; 127 NSPredicate * regextestct = [NSPredicate primary: @ "self matches % @", CT]; 128 129 if ([regextestmobile evaluateWithObject: mobileNum] = YES) 130 | ([regextestcm evaluateWithObject: mobileNum] = YES) 131 | ([regextestct evaluateWithObject: mobileNum] = YES) 132 | ([regextestcu evaluateWithObject: mobileNum] = YES) 133 {134 if ([regextestcm limit: mobileNum] = YES) {135 NSLog (@ "China Mobile"); 136} else if ([regextestct evaluateWithObject: mobileNum] = YES) {137 NSLog (@ "Unicom"); 138} else if ([regextestcu evaluateWithObject: mobileNum] = YES) {139 NSLog (@ "Telecom "); 140} else {141 NSLog (@ "Unknow"); 142} 143 144 return YES; 145} 146 else147 {148 return NO; 149} 150} 151 @ end

1. query products with the number of products less than 9

The code here is very simple. The first step is to create a filter, replace number 9 with placeholders, the filter returns a new array, then traverse the array, and only take the product name.

// Number less than 9 define the predicate containing the filter condition NSPredicate * prdicate = [NSPredicate predicateWithFormat: @ "productCount <% d", 9]; // The new array NSArray * newArray = [sproducts filteredArrayUsingPredicate: prdicate]; for (Products * item in newArray) {NSLog (@ "newArray = % @", item. productName );}

2. query products with a quantity greater than 9 and productname equal to "Samsung jfggg"

// The number is greater than 9 and productname is equal to "Samsung jfggg". The defined predicateWithFormat includes the filter condition prdicate = [NSPredicate predicateWithFormat: @ "productName = 'samsung '& productCount> 9"]; // The new array newArray = [sproducts filteredArrayUsingPredicate: prdicate] is returned in the filter result.

3. in inclusion (* Note inclusion is full-character matching)

Prdicate = [NSPredicate predicateWithFormat: @ "productName IN {'G', 'huawei ', 'samsung'} | productCount IN {2, 5}"]; // The new array newArray = [sproducts filteredArrayUsingPredicate: prdicate] is returned in the filter result.

4. String-Related Processing

// Prdicate = [NSPredicate predicateWithFormat: @ "productName BEGINSWITH 'A'"]; // prdicate whose productName ends with ba = [NSPredicate predicateWithFormat: @ "productName ENDSWITH 'G'"]; // prdicate = [NSPredicate predicateWithFormat: @ "productName CONTAINS 'A'"];

5. like wildcard for fuzzy search

// Like matches any number of characters. // The condition prdicate = [NSPredicate predicateWithFormat: @ "productName like '* s *'"] is met as long as there are s characters in productName; //? The following query condition indicates that the second character in name is prdicate = [NSPredicate predicateWithFormat: @ "productName like '? S * '"]; newArray = [sproducts filteredArrayUsingPredicate: prdicate];

6. Regular Expression. The example is to verify whether it is a mobile phone number.

// Regular Expression string NSString * MOBILE = @ "^ 1 (3 [0-9] | 5 [0-35-9] | 8 [025-9]) \ d {8} $ "; // create a handsome selector NSPredicate * regextestmobile = [NSPredicate predicateWithFormat: @" self matches % @ ", MOBILE]; // The evaluateWithObject method of the filter reversely verifies whether the mobile phone number is used. The bool value BOOL isPhoneNum = [regextestmobile evaluateWithObject: @ "15300250500"] is returned.

 

We only list several common usage of predicates, and there are many flexible usage methods, for example, for Interval filtering of time datetime and predicate variable "Predicate = $ variable name", we hope you will study it later.