Search and query IOS NSPredicate

Brief description: NSPredicate in the Cocoa framework is used for queries. Its principles and usage are similar to where in SQL, and its function is equivalent to database filtering.

The most common functions

+ (NSPredicate *)predicateWithFormat:(NSString *)predicateFormat, ...;

1. Comparison operators>, <, =, >=, <=, and ,! =
Example: @ "number> = 99"

 

2. Range operators: IN and
Example: @ "number BETWEEN {1, 5 }"
@ "Address IN {'shanghai', 'nanjing '}"

3. string itself: SELF
Example: @ "SELF = 'apple '"

4. String-related: BEGINSWITH, ENDSWITH, and CONTAINS
Example: @ "name CONTAIN [cd] 'ang '" // contains a string
@ "Name BEGINSWITH [c] 'sh'" // starts with a string
@ "Name ENDSWITH [d] 'ang '" // end with a string
Note: [c] is case-insensitive, and [d] is case-insensitive. That is, there is no accent. [cd] is case-insensitive and does not distinguish between pronunciation symbols.

5. wildcard: LIKE
For example, @ "name LIKE [cd] '* er *'" // * Indicates a wildcard, and Like also accepts [cd].
@ "Name LIKE [cd] '??? Er *'"

 

6. Regular Expression: MATCHES
For example, NSString * regex = @ "^ A. + e $"; // starts with A and ends with e.
@ "Name MATCHES % @", regex

 

Practical Application: filtering NSArray

NSArray *array = [[NSArray alloc]initWithObjects:@"beijing",@"shanghai",@"guangzou",@"wuhan", nil];  NSString *string = @"ang";  NSPredicate *pred = [NSPredicate predicateWithFormat:@"SELF CONTAINS %@",string];  NSLog(@"%@",[array filteredArrayUsingPredicate:pred]);  

 

Practical Application: Determine whether the first letter of a string is a letter

NSString *regex = @"[A-Za-z]+";  NSPredicate *predicate = [NSPredicate predicateWithFormat:@"SELF MATCHES %@", regex];    if ([predicate evaluateWithObject:aString]) {  }  

 

Practical Application: String replacement

NSError* error = NULL;  NSRegularExpression* regex = [NSRegularExpression regularExpressionWithPattern:@"(encoding=\")[^\"]+(\")"                                                                              options:0                                                                              error:&error];  NSString* sample = @"<xml encoding=\"abc\"></xml><xml encoding=\"def\"></xml><xml encoding=\"ttt\"></xml>";  NSLog(@"Start:%@",sample);  NSString* result = [regex stringByReplacingMatchesInString:sample                                                        options:0                                                         range:NSMakeRange(0, sample.length)                                                        withTemplate:@"$1utf-8$2"];  NSLog(@"Result:%@", result);  

 

Practical Application: intercepting strings

// Assemble a string, you need to parse the URL NSString * urlString = @ "<meta/> <link/> <title> 1Q84 BOOK1 </title> 
 
Practical Application: mobile phone number and phone number Function
// Regular expression to determine the mobile phone number address format-(BOOL) isMobileNumber :( NSString *) mobileNum {/*** mobile phone number *: 134 [0-8], 135,136,137,138,139,150,151,157,158,159,182,187,188 * Unicom: 130,131,132,152,155,156,185,186 * China Telecom: 133,1349, 153,180,189 */NSString * MOBILE = @ "^ 1 (3 [0-9] | 5 [0-35-9] | 8 [025-9]) \ d {8} $ ";/** 10 * China Mobile: China Mobile 11*134 [0-8], 135,136,137,138,139,150,151,157,158,159,182,187,188 12 */NSString * CM = @ "^ 1 (34 [0-8] | (3 [5-9] | 5 [017-9] | 8 [278]) \ d) \ d {7} $ ";/** 15 * China Unicom: china Unicom 16*130,131,132,152,155,156,185,186 17 */NSString * CU = @ "^ 1 (3 [0-2] | 5 [1, 256] | 8 [56]) \ d {8} $ ";/** 20 * China Telecom: China Telecom 21*133,1349, 153,180,189 22 */NSString * CT = @ "^ 1 (33 | 53 | 8 [09]) [0-9] | 349) \ d {7} $ "; /** 25 * fixed lines in mainland China and PHS 26 * area code: 010,020,021,022,023,024,025,027,028,029 27 * No: seven or eight digits 28 * // NSString * PHS = @ "^ 0 (10 | 2 [0-5789] | \ d {3 }) \ d {7,8} $ "; NSPredicate * regextestmobile = [NSPredicate response: @" self matches % @ ", MOBILE]; NSPredicate * regextestcm = [NSPredicate predicateWithFormat: @ "self matches % @", CM]; NSPredicate * regextestcu = [NSPredicate predicateWithFormat: @ "self matches % @", CU]; NSPredicate * regextestct = [NSPredicate response: @ "self matches % @", CT]; if ([regextestmobile evaluateWithObject: mobileNum] = YES) | ([regextestcm evaluateWithObject: mobileNum] = YES) | ([regextestct failed: mobileNum] = YES) | ([regextestcu evaluateWithObject: mobileNum] = YES) {if ([regextestcm evaluateWithObject: mobileNum] = YES) {NSLog (@ "China Mobile");} else if ([regextestct evaluateWithObject: mobileNum] = YES) {NSLog (@ "China Telecom ");} else if ([regextestcu evaluateWithObject: mobileNum] = YES) {NSLog (@ "China Unicom");} else {NSLog (@ "Unknow");} return YES ;} else {return NO ;}}
 
Practical Application: email verification and phone number verification
// Whether it is a valid regular expression + (BOOL) isValidateRegularExpression :( NSString *) strDestination byExpression :( NSString *) strExpression {NSPredicate * predicate = [identifier: @ "self matches % @", strExpression]; return [predicate evaluateWithObject: strDestination];} // verify email + (BOOL) isValidateEmail :( NSString *) email {NSString * strRegex = @ "[A-Z0-9a-z. _ % +-] + @ [A-Za-z0-9. -] + \\. [A-Za-z] {1, 5} "; BOOL rt = [CommonTools isValidateRegularExpression: email byExpression: strRegex]; return rt;} // verify the phone number + (BOOL) isValidateTelNumber :( NSString *) number {NSString * strRegex = @ "[0-9] {1, 20}"; BOOL rt = [CommonTools isValidateRegularExpression: number byExpression: strRegex]; return rt ;}
 
Practical Application: NSDate for filtering
// Within ten days: NSDate * endDate = [[NSDate date] retain]; NSTimeInterval timeInterval = [endDate timeIntervalSinceReferenceDate]; timeInterval-= 3600*24*10; NSDate * beginDate = [[NSDate Duration: timeInterval] retain]; // filter coredata (assuming fetchRequest is available) NSPredicate * predicate_date = [NSPredicate predicateWithFormat: @ "date >=% @ AND date <= % @", beginDate, endDate]; [fetchRequest setPredicate: predicate_date]; // release retained object [endDate release]; [beginDate release];