站長資訊網(wǎng)何謂正則表達(dá)式
正則表達(dá)式（regular expression），在計(jì)算機(jī)科學(xué)中，是指一個(gè)用來描述或者匹配一系列符合某個(gè)句法規(guī)則的字符串的單個(gè)字符串。在很多文本編輯器或其他工具里，正則表達(dá)式通常被用來檢索和/或替換那些符合某個(gè)模式的文本內(nèi)容。正則表達(dá)式這個(gè)概念最初是由Unix中的工具軟件（例如sed和grep）普及開的。正則表達(dá)式通常縮寫成“regex”，單數(shù)有regexp、regex，復(fù)數(shù)有regexps、regexes、regexen。
正則表達(dá)式組成
正則表達(dá)式有兩種類型的字符組成
第一種：用來匹配的字符，或者叫常規(guī)字符
第二種：控制字符或具有特殊含義的元字符
iphone 4.0以后就開始支持正則表達(dá)式的使用了，在ios4.0中正則表達(dá)式的使用是使用NSRegularExpression類來調(diào)用。
1. 下面一個(gè)簡單的使用正則表達(dá)式的一個(gè)例子：NSRegularExpression 類
-(void)parseString{ //組裝一個(gè)字符串，需要把里面的網(wǎng)址解析出來 NSString *urlString=@"sfdsfhttp://www.baidu.com"; //NSRegularExpression類里面調(diào)用表達(dá)的方法需要傳遞一個(gè)NSError的參數(shù)。下面定義一個(gè) NSError *error; //http+:[^\s]* 這個(gè)表達(dá)式是檢測一個(gè)網(wǎng)址的。 NSRegularExpression *regex = [NSRegularExpression regularExpressionWithPattern:@"http+:[^\s]*" options:0 error:&error]; if (regex != nil) { NSTextCheckingResult *firstMatch=[regex firstMatchInString:urlString options:0range:NSMakeRange(0, [urlString length])]; if (firstMatch) { NSRange resultRange = [firstMatch rangeAtIndex:0]; //等同于 firstMatch.range --- 相匹配的范圍 //從urlString當(dāng)中截取數(shù)據(jù) NSString *result=[urlString substringWithRange:resultRange]; //輸出結(jié)果 NSLog(@"%@",result); } } }
2.使用正則表達(dá)式來判斷
//初始化一個(gè)NSRegularExpression 對(duì)象，并設(shè)置檢測對(duì)象范圍為：0-9 NSRegularExpression *regex2 = [NSRegularExpression regularExpressionWithPattern:@"^[0-9]*$" options:0 error:nil]; if (regex2) {//對(duì)象進(jìn)行匹配 NSTextCheckingResult *result2 = [regex2 firstMatchInString:textField.text options:0 range:NSMakeRange(0, [textField.text length])]; if (result2) { } }
1.判斷郵箱格式是否正確的代碼：NSPredicatel類
//利用正則表達(dá)式驗(yàn)證
NSPredicatel類:主要用來指定過濾器的條件,該對(duì)象可以準(zhǔn)確的描述所需條件，對(duì)每個(gè)對(duì)象通過謂詞進(jìn)行篩選，判斷是否與條件相匹配。謂詞是指在計(jì)算機(jī)中表示計(jì)算真假值的函數(shù)。原理和用法都類似于SQL查詢中的where，作用相當(dāng)于數(shù)據(jù)庫的過濾取。主要用于從集合中分揀出符合條件的對(duì)象，也可以用于字符串的正則匹配
-(BOOL)isValidateEmail:(NSString *)email { NSString *emailRegex = @"[A-Z0-9a-z._%+-]+@[A-Za-z0-9.-]+\.[A-Za-z]{2,4}"; NSPredicate *emailTest = [NSPredicate predicateWithFormat:@"SELF MATCHES%@",emailRegex]; return [emailTest evaluateWithObject:email]; }
2.匹配9-15個(gè)由字母/數(shù)字組成的字符串的正則表達(dá)式：
NSString * regex = @"^[A-Za-z0-9]{9,15}$"; NSPredicate *pred = [NSPredicate predicateWithFormat:@"SELF MATCHES %@", regex]; BOOL isMatch = [pred evaluateWithObject:txtfldPhoneNumber.text];
Cocoa用NSPredicate描述查詢的方式，原理類似于在數(shù)據(jù)庫中進(jìn)行查詢
用BETWEEN，IN，BEGINWITH，ENDWITH，CONTAINS，LIKE這些謂詞來構(gòu)造NSPredicate，必要的時(shí)候使用SELF直接對(duì)自己進(jìn)行匹配
//基本的查詢 NSPredicate *predicate; predicate = [NSPredicate predicateWithFormat: @"name == 'Herbie'"]; BOOL match = [predicate evaluateWithObject: car]; NSLog (@"%s", (match) ? "YES" : "NO"); //在整個(gè)cars里面循環(huán)比較 predicate = [NSPredicate predicateWithFormat: @"engine.horsepower > 150"]; NSArray *cars = [garage cars]; for (Car *car in [garage cars]) { if ([predicate evaluateWithObject: car]) { NSLog (@"%@", car.name); } } //輸出完整的信息 predicate = [NSPredicate predicateWithFormat: @"engine.horsepower > 150"]; NSArray *results; results = [cars filteredArrayUsingPredicate: predicate]; NSLog (@"%@", results); //含有變量的謂詞 NSPredicate *predicateTemplate = [NSPredicate predicateWithFormat:@"name == $NAME"]; NSDictionary *varDict; varDict = [NSDictionary dictionaryWithObjectsAndKeys: @"Herbie", @"NAME", nil]; predicate = [predicateTemplate predicateWithSubstitutionVariables: varDict]; NSLog(@"SNORGLE: %@", predicate); match = [predicate evaluateWithObject: car]; NSLog (@"%s", (match) ? "YES" : "NO"); //注意不能使用$VARIABLE作為路徑名，因?yàn)樗荡碇? //謂詞字符竄還支持c語言中一些常用的運(yùn)算符 predicate = [NSPredicate predicateWithFormat: @"(engine.horsepower > 50) AND (engine.horsepower < 200)"]; results = [cars filteredArrayUsingPredicate: predicate]; NSLog (@"oop %@", results); predicate = [NSPredicate predicateWithFormat: @"name < 'Newton'"]; results = [cars filteredArrayUsingPredicate: predicate]; NSLog (@"%@", [results valueForKey: @"name"]); //強(qiáng)大的數(shù)組運(yùn)算符 predicate = [NSPredicate predicateWithFormat: @"engine.horsepower BETWEEN { 50, 200 }"]; results = [cars filteredArrayUsingPredicate: predicate]; NSLog (@"%@", results); NSArray *betweens = [NSArray arrayWithObjects: [NSNumber numberWithInt: 50], [NSNumber numberWithInt: 200], nil]; predicate = [NSPredicate predicateWithFormat: @"engine.horsepower BETWEEN %@", betweens]; results = [cars filteredArrayUsingPredicate: predicate]; NSLog (@"%@", results); predicateTemplate = [NSPredicate predicateWithFormat: @"engine.horsepower BETWEEN $POWERS"]; varDict = [NSDictionary dictionaryWithObjectsAndKeys: betweens, @"POWERS", nil]; predicate = [predicateTemplate predicateWithSubstitutionVariables: varDict]; results = [cars filteredArrayUsingPredicate: predicate]; NSLog (@"%@", results); //IN運(yùn)算符 predicate = [NSPredicate predicateWithFormat: @"name IN { 'Herbie', 'Snugs', 'Badger', 'Flap' }"]; results = [cars filteredArrayUsingPredicate: predicate]; NSLog (@"%@", [results valueForKey: @"name"]); predicate = [NSPredicate predicateWithFormat: @"SELF.name IN { 'Herbie', 'Snugs', 'Badger', 'Flap' }"]; results = [cars filteredArrayUsingPredicate: predicate]; NSLog (@"%@", [results valueForKey: @"name"]); names = [cars valueForKey: @"name"]; predicate = [NSPredicate predicateWithFormat: @"SELF IN { 'Herbie', 'Snugs', 'Badger', 'Flap' }"]; results = [names filteredArrayUsingPredicate: predicate];//這里限制了SELF的范圍 NSLog (@"%@", results); //BEGINSWITH,ENDSWITH,CONTAINS //附加符號(hào)，[c],[d],[cd],c表示不區(qū)分大小寫，d表示不區(qū)分發(fā)音字符，cd表示什么都不區(qū)分 predicate = [NSPredicate predicateWithFormat: @"name BEGINSWITH 'Bad'"]; results = [cars filteredArrayUsingPredicate: predicate]; NSLog (@"%@", results); predicate = [NSPredicate predicateWithFormat: @"name BEGINSWITH 'HERB'"]; results = [cars filteredArrayUsingPredicate: predicate]; NSLog (@"%@", results); predicate = [NSPredicate predicateWithFormat: @"name BEGINSWITH[cd] 'HERB'"]; results = [cars filteredArrayUsingPredicate: predicate]; NSLog (@"%@", results); //LIKE運(yùn)算符（通配符） predicate = [NSPredicate predicateWithFormat: @"name LIKE[cd] '*er*'"]; results = [cars filteredArrayUsingPredicate: predicate]; NSLog (@"%@", results); predicate = [NSPredicate predicateWithFormat: @"name LIKE[cd] '???er*'"]; results = [cars filteredArrayUsingPredicate: predicate]; NSLog (@"%@", results); //基本的查詢 NSPredicate *predicate; predicate = [NSPredicate predicateWithFormat: @"name == 'Herbie'"]; BOOL match = [predicate evaluateWithObject: car]; NSLog (@"%s", (match) ? "YES" : "NO"); //在整個(gè)cars里面循環(huán)比較 predicate = [NSPredicate predicateWithFormat: @"engine.horsepower > 150"]; NSArray *cars = [garage cars]; for (Car *car in [garage cars]) { if ([predicate evaluateWithObject: car]) { NSLog (@"%@", car.name); } } //輸出完整的信息 predicate = [NSPredicate predicateWithFormat: @"engine.horsepower > 150"]; NSArray *results; results = [cars filteredArrayUsingPredicate: predicate]; NSLog (@"%@", results); //含有變量的謂詞 NSPredicate *predicateTemplate = [NSPredicate predicateWithFormat:@"name == $NAME"]; NSDictionary *varDict; varDict = [NSDictionary dictionaryWithObjectsAndKeys: @"Herbie", @"NAME", nil]; predicate = [predicateTemplate predicateWithSubstitutionVariables: varDict]; NSLog(@"SNORGLE: %@", predicate); match = [predicate evaluateWithObject: car]; NSLog (@"%s", (match) ? "YES" : "NO"); //注意不能使用$VARIABLE作為路徑名，因?yàn)樗荡碇? //謂詞字符竄還支持c語言中一些常用的運(yùn)算符 predicate = [NSPredicate predicateWithFormat: @"(engine.horsepower > 50) AND (engine.horsepower < 200)"]; results = [cars filteredArrayUsingPredicate: predicate]; NSLog (@"oop %@", results); predicate = [NSPredicate predicateWithFormat: @"name < 'Newton'"]; results = [cars filteredArrayUsingPredicate: predicate]; NSLog (@"%@", [results valueForKey: @"name"]); //強(qiáng)大的數(shù)組運(yùn)算符 predicate = [NSPredicate predicateWithFormat: @"engine.horsepower BETWEEN { 50, 200 }"]; results = [cars filteredArrayUsingPredicate: predicate]; NSLog (@"%@", results); NSArray *betweens = [NSArray arrayWithObjects: [NSNumber numberWithInt: 50], [NSNumber numberWithInt: 200], nil]; predicate = [NSPredicate predicateWithFormat: @"engine.horsepower BETWEEN %@", betweens]; results = [cars filteredArrayUsingPredicate: predicate]; NSLog (@"%@", results); predicateTemplate = [NSPredicate predicateWithFormat: @"engine.horsepower BETWEEN $POWERS"]; varDict = [NSDictionary dictionaryWithObjectsAndKeys: betweens, @"POWERS", nil]; predicate = [predicateTemplate predicateWithSubstitutionVariables: varDict]; results = [cars filteredArrayUsingPredicate: predicate]; NSLog (@"%@", results); //IN運(yùn)算符 predicate = [NSPredicate predicateWithFormat: @"name IN { 'Herbie', 'Snugs', 'Badger', 'Flap' }"]; results = [cars filteredArrayUsingPredicate: predicate]; NSLog (@"%@", [results valueForKey: @"name"]); predicate = [NSPredicate predicateWithFormat: @"SELF.name IN { 'Herbie', 'Snugs', 'Badger', 'Flap' }"]; results = [cars filteredArrayUsingPredicate: predicate]; NSLog (@"%@", [results valueForKey: @"name"]); names = [cars valueForKey: @"name"]; predicate = [NSPredicate predicateWithFormat: @"SELF IN { 'Herbie', 'Snugs', 'Badger', 'Flap' }"]; results = [names filteredArrayUsingPredicate: predicate];//這里限制了SELF的范圍 NSLog (@"%@", results); //BEGINSWITH,ENDSWITH,CONTAINS //附加符號(hào)，[c],[d],[cd],c表示不區(qū)分大小寫，d表示不區(qū)分發(fā)音字符，cd表示什么都不區(qū)分 predicate = [NSPredicate predicateWithFormat: @"name BEGINSWITH 'Bad'"]; results = [cars filteredArrayUsingPredicate: predicate]; NSLog (@"%@", results); predicate = [NSPredicate predicateWithFormat: @"name BEGINSWITH 'HERB'"]; results = [cars filteredArrayUsingPredicate: predicate]; NSLog (@"%@", results); predicate = [NSPredicate predicateWithFormat: @"name BEGINSWITH[cd] 'HERB'"]; results = [cars filteredArrayUsingPredicate: predicate]; NSLog (@"%@", results); //LIKE運(yùn)算符（通配符） predicate = [NSPredicate predicateWithFormat: @"name LIKE[cd] '*er*'"]; results = [cars filteredArrayUsingPredicate: predicate]; NSLog (@"%@", results); predicate = [NSPredicate predicateWithFormat: @"name LIKE[cd] '???er*'"]; results = [cars filteredArrayUsingPredicate: predicate]; NSLog (@"%@", results);
以上就是小編給大家分享的iOS中使用正則表達(dá)式NSRegularExpression 來驗(yàn)證textfiled輸入的內(nèi)容，希望大家喜歡。
