一般来说这种情况还是蛮多的,比如你从文件中读入了一个array1,然后想把程序中的一个array2中符合array1中内容的元素过滤出来。
正 常傻瓜一点就是两个for循环,一个一个进行比较,这样效率不高,而且代码也不好看。
其实一个循环或者无需循环就可以搞定了,那就需要用搞 NSPredicate这个类了~膜拜此类~
1)例子一,一个循环
NSArray *arrayFilter = [NSArray arrayWithObjects:@"pict", @"blackrain", @"ip", nil]; NSArray *arrayContents = [NSArray arrayWithObjects:@"I am a picture.", @"I am a guy", @"I am gagaga", @"ipad", @"iphone", nil]; |
我想过滤arrayContents的话只要循环 arrayFilter就好了
int i = 0, count = [arrayFilter count]; for(i = 0; i < count; i ++) { NSString *arrayItem = (NSString *)[arrayFilter objectAtIndex:i]; NSPredicate *filterPredicate = [[NSPredicate predicateWithFormat:@"SELF CONTAINS %@", arrayItem]; NSLog(@"Filtered array with filter %@, %@", arrayItem, [arrayContents filteredArrayUsingPredicate:filterPredicate]); } |
当然以上代码中arrayContent最好用mutable 的,这样就可以直接filter了,NSArray是不可修改的。
2)例子二,无需循环
NSArray *arrayFilter = [NSArray arrayWithObjects:@"abc1", @"abc2", nil]; NSArray *arrayContent = [NSArray arrayWithObjects:@"a1", @"abc1", @"abc4", @"abc2", nil]; NSPredicate *thePredicate = [NSPredicate predicateWithFormat:@"NOT (SELF in %@)", arrayFilter]; [arrayContent filterUsingPredicate:thePredicate]; |
这样arrayContent过滤出来的就是不包含 arrayFilter中的所有item了。
3)生成文件路径下文件集合列表
NSFileManager *fileManager = [NSFileManager defaultManager];
NSString *defaultPath = [[NSBundle mainBundle] resourcePath];
NSError *error;
NSArray *directoryContents = [fileManager contentsOfDirectoryAtPath:defaultPath error:&error]
4)match的用法
1. 简单比较
NSString *match = @"imagexyz-999.png";
NSPredicate *predicate = [NSPredicate predicateWithFormat:@"SELF == %@", match];
NSArray *results = [directoryContents filteredArrayUsingPredicate:predicate];
2. match里like的用法(类似Sql中的用法)
NSString *match = @"imagexyz*.png";
NSPredicate *predicate = [NSPredicate predicateWithFormat:@"SELF like %@", match];
NSArray *results = [directoryContents filteredArrayUsingPredicate:predicate];3. 大小写比较
[c]表示忽略大小写,[d]表示忽略重音,可以在一起使用,如下:
NSString *match = @"imagexyz*.png";
NSPredicate *predicate = [NSPredicate predicateWithFormat:@"SELF like[cd] %@", match];
NSArray *results = [directoryContents filteredArrayUsingPredicate:predicate];
4.使用正则
NSString *match = @"imagexyz-\\d{3}\\.png"; //imagexyz-123.png
NSPredicate *predicate = [NSPredicate predicateWithFormat:@"SELF matches %@", match];
NSArray *results = [directoryContents filteredArrayUsingPredicate:predicate];
总结:
1) 当使用聚合类的操作符时是可以不需要循环的
2)当使用单个比较类的操作符时可以一个循环来搞定
PS,例子 一中尝试使用[@"SELF CONTAINS %@", arrayFilter] 来过滤会挂调,因为CONTAINS时字符串比较操作符,不是集合操作符。
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简述:Cocoa框架中的NSPredicate用于查询,原理和用法都类似于SQL中的where,作用相当于数据库的过滤取。
定义(最常用到的方法):
- NSPredicate*ca=[NSPredicatepredicateWithFormat:(NSString*),...];
Format:
(1)比较运算符>,<,==,>=,<=,!=
可用于数值及字符串
例:@"number > 100"
(2)范围运算符:IN、BETWEEN
例:@"number BETWEEN {1,5}"
@"address IN {'shanghai','beijing'}"
(3)字符串本身:SELF
例:@“SELF == ‘APPLE’"
(4)字符串相关:BEGINSWITH、ENDSWITH、CONTAINS
例:@"name CONTAIN[cd] 'ang'" //包含某个字符串
@"name BEGINSWITH[c] 'sh'" //以某个字符串开头
@"name ENDSWITH[d] 'ang'" //以某个字符串结束
注:[c]不区分大小写[d]不区分发音符号即没有重音符号[cd]既不区分大小写,也不区分发音符号。
(5)通配符:LIKE
例:@"name LIKE[cd] '*er*'" //*代表通配符,Like也接受[cd].
@"name LIKE[cd] '???er*'"
(6)正则表达式:MATCHES
例:NSString *regex = @"^A.+e$"; //以A开头,e结尾
@"name MATCHES %@",regex
实际应用:
(1)对NSArray进行过滤
- NSArray*array=[[NSArrayalloc]initWithObjects:@"beijing",@"shanghai",@"guangzou",@"wuhan",nilnil];
- NSString*string=@"ang";
- NSPredicate*pred=[NSPredicatepredicateWithFormat:@"SELFCONTAINS%@",string];
- NSLog(@"%@",[arrayfilteredArrayUsingPredicate:pred]);
(2)判断字符串首字母是否为字母:
- NSString*regex=@"[A-Za-z]+";
- NSPredicate*predicate=[NSPredicatepredicateWithFormat:@"SELFMATCHES%@",regex];
- if([predicateevaluateWithObject:aString]){
- }
(3)字符串替换:
- NSError*error=NULL;
- NSRegularExpression*regex=[NSRegularExpressionregularExpressionWithPattern:@"(encoding=\")[^\"]+(\")"
- options:0
- error:&error];
- NSString*sample=@"<xmlencoding=\"abc\"></xml><xmlencoding=\"def\"></xml><xmlencoding=\"ttt\"></xml>";
- NSLog(@"Start:%@",sample);
- NSString*result=[regexstringByReplacingMatchesInString:sample
- options:0
- range:NSMakeRange(0,sample.length)
- withTemplate:@"$1utf-8$2"];
- NSLog(@"Result:%@",result);
(4)截取字符串:
- //组装一个字符串,需要把里面的网址解析出来
- NSString*urlString=@"<meta/><link/><title>1Q84BOOK1</title></head><body>";
- //NSRegularExpression类里面调用表达的方法需要传递一个NSError的参数。下面定义一个
- NSError*error;
- //http+:[^\\s]*这个表达式是检测一个网址的。(?<=title\>).*(?=</title)截取html文章中的<title></title>中内文字的正则表达式
- NSRegularExpression*regex=[NSRegularExpressionregularExpressionWithPattern:@"(?<=title\\>).*(?=</title)"options:0error:&error];
- if(regex!=nil){
- NSTextCheckingResult*firstMatch=[regexfirstMatchInString:urlStringoptions:0range:NSMakeRange(0,[urlStringlength])];
- if(firstMatch){
- NSRangeresultRange=[firstMatchrangeAtIndex:0];
- //从urlString当中截取数据
- NSString*result=[urlStringsubstringWithRange:resultRange];
- //输出结果
- NSLog(@"->%@<-",result);
- }
- }
(5)判断手机号码,电话号码函数
- //正则判断手机号码地址格式
- -(BOOL)isMobileNumber:(NSString*)mobileNum
- {
- /**
- *手机号码
- *移动:134[0-8],135,136,137,138,139,150,151,157,158,159,182,187,188
- *联通:130,131,132,152,155,156,185,186
- *电信:133,1349,153,180,189
- */
- NSString*MOBILE=@"^1(3[0-9]|5[0-35-9]|8[025-9])\\d{8}$";
- /**
- *中国移动:ChinaMobile
- *134[0-8],135,136,137,138,139,150,151,157,158,159,182,187,188
- */
- NSString*CM=@"^1(34[0-8]|(3[5-9]|5[017-9]|8[278])\\d)\\d{7}$";
- /**
- *中国联通:ChinaUnicom
- *130,131,132,152,155,156,185,186
- */
- NSString*CU=@"^1(3[0-2]|5[256]|8[56])\\d{8}$";
- /**
- *中国电信:ChinaTelecom
- *133,1349,153,180,189
- */
- NSString*CT=@"^1((33|53|8[09])[0-9]|349)\\d{7}$";
- /**
- *大陆地区固话及小灵通
- *区号:010,020,021,022,023,024,025,027,028,029
- *号码:七位或八位
- */
- //NSString*PHS=@"^0(10|2[0-5789]|\\d{3})\\d{7,8}$";
- NSPredicate*regextestmobile=[NSPredicatepredicateWithFormat:@"SELFMATCHES%@",MOBILE];
- NSPredicate*regextestcm=[NSPredicatepredicateWithFormat:@"SELFMATCHES%@",CM];
- NSPredicate*regextestcu=[NSPredicatepredicateWithFormat:@"SELFMATCHES%@",CU];
- NSPredicate*regextestct=[NSPredicatepredicateWithFormat:@"SELFMATCHES%@",CT];
- if(([regextestmobileevaluateWithObject:mobileNum]==YES)
- ||([regextestcmevaluateWithObject:mobileNum]==YES)
- ||([regextestctevaluateWithObject:mobileNum]==YES)
- ||([regextestcuevaluateWithObject:mobileNum]==YES))
- {
- if([regextestcmevaluateWithObject:mobileNum]==YES){
- NSLog(@"ChinaMobile");
- }elseif([regextestctevaluateWithObject:mobileNum]==YES){
- NSLog(@"ChinaTelecom");
- }elseif([regextestcuevaluateWithObject:mobileNum]==YES){
- NSLog(@"ChinaUnicom");
- }else{
- NSLog(@"Unknow");
- }
- returnYES;
- }
- else
- {
- returnNO;
- }
- }
(6)邮箱验证、电话号码验证:
- //是否是有效的正则表达式
- +(BOOL)isValidateRegularExpression:(NSString*)strDestinationbyExpression:(NSString*)strExpression
- {
- NSPredicate*predicate=[NSPredicatepredicateWithFormat:@"SELFMATCHES%@",strExpression];
- return[predicateevaluateWithObject:strDestination];
- }
- //验证email
- +(BOOL)isValidateEmail:(NSString*)email{
- NSString*strRegex=@"[A-Z0-9a-z._%+-]+@[A-Za-z0-9.-]+\\.[A-Za-z]{1,5}";
- BOOLrt=[CommonToolsisValidateRegularExpression:emailbyExpression:strRegex];
- returnrt;
- }
- //验证电话号码
- +(BOOL)isValidateTelNumber:(NSString*)number{
- NSString*strRegex=@"[0-9]{1,20}";
- BOOLrt=[CommonToolsisValidateRegularExpression:numberbyExpression:strRegex];
- returnrt;
- }
(7)NSDate进行筛选
- //日期在十天之内:
- NSDate*endDate=[[NSDatedate]retain];
- NSTimeIntervaltimeInterval=[endDatetimeIntervalSinceReferenceDate];
- timeInterval-=3600*24*10;
- NSDate*beginDate=[[NSDatedateWithTimeIntervalSinceReferenceDate:timeInterval]retain];
- //对coredata进行筛选(假设有fetchRequest)
- NSPredicate*predicate_date=
- [NSPredicatepredicateWithFormat:@"date>=%@ANDdate<=%@",beginDate,endDate];
- [fetchRequestsetPredicate:predicate_date];
- //释放retained的对象
- [endDaterelease];
- [beginDaterelease];
NSPredicate是一个Foundation类,它指定数据被获取或者过滤的方式。它的查询语言就像SQL的WHERE和正则表达式的交叉一样,提供了具有表现力的,自然语言界面来定义一个集合被搜寻的逻辑条件。
“ ”NSPredicate是一个Foundation类,它指定数据被获取或者过滤的方式。它的查询语言就像SQL的WHERE和正则表达式的交叉一样,提供了具有表现力的,自然语言界面来定义一个集合被搜寻的逻辑条件。
索引 | 1 | 2 | 3 | 4 |
名 | Alice | Bob | Charlie | Quentin |
姓 | Smith | Jones | Smith | Alberts |
年龄 | 24 | 27 | 33 | 31 |
- @interfacePerson:NSObject
- @propertyNSString*firstName;
- @propertyNSString*lastName;
- @propertyNSNumber*age;
- @end
- @implementationPerson
- -(NSString*)description{
- return[NSStringstringWithFormat:@"%@%@",self.firstName,self.lastName];
- }
- @end
- #pragmamark-
- NSArray*firstNames=@[@"Alice",@"Bob",@"Charlie",@"Quentin"];
- NSArray*lastNames=@[@"Smith",@"Jones",@"Smith",@"Alberts"];
- NSArray*ages=@[@24,@27,@33,@31];
- NSMutableArray*people=[NSMutableArrayarray];
- [firstNamesenumerateObjectsUsingBlock:^(idobj,NSUIntegeridx,BOOL*stop){
- Person*person=[[Personalloc]init];
- person.firstName=firstNames[idx];
- person.lastName=lastNames[idx];
- person.age=ages[idx];
- [peopleaddObject:person];
- }];
- NSPredicate*bobPredicate=[NSPredicatepredicateWithFormat:@"firstName='Bob'"];
- NSPredicate*smithPredicate=[NSPredicatepredicateWithFormat:@"lastName=%@",@"Smith"];
- NSPredicate*thirtiesPredicate=[NSPredicatepredicateWithFormat:@"age>=30"];
- //["BobJones"]
- NSLog(@"Bobs:%@",[peoplefilteredArrayUsingPredicate:bobPredicate]);
- //["AliceSmith","CharlieSmith"]
- NSLog(@"Smiths:%@",[peoplefilteredArrayUsingPredicate:smithPredicate]);
- //["CharlieSmith","QuentinAlberts"]
- NSLog(@"30's:%@",[peoplefilteredArrayUsingPredicate:thirtiesPredicate]);
- NSPredicate*ageIs33Predicate=[NSPredicatepredicateWithFormat:@"%K=%@",@"age",@33];
- //["CharlieSmith"]
- NSLog(@"Age33:%@",[peoplefilteredArrayUsingPredicate:ageIs33Predicate]);
- NSPredicate*namesBeginningWithLetterPredicate=[NSPredicatepredicateWithFormat:@"(firstNameBEGINSWITH[cd]$letter)OR(lastNameBEGINSWITH[cd]$letter)"];
- //["AliceSmith","QuentinAlberts"]
- NSLog(@"'A'Names:%@",[peoplefilteredArrayUsingPredicate:[namesBeginningWithLetterPredicatepredicateWithSubstitutionVariables:@{@"letter":@"A"}]]);
- [NSCompoundPredicateandPredicateWithSubpredicates:@[[NSPredicatepredicateWithFormat:@"age>25"],[NSPredicatepredicateWithFormat:@"firstName=%@",@"Quentin"]]];
- [NSPredicatepredicateWithFormat:@"(age>25)AND(firstName=%@)",@"Quentin"];
- +(NSPredicate*)predicateWithLeftExpression:(NSExpression*)lhs
- rightExpression:(NSExpression*)rhs
- modifier:(NSComparisonPredicateModifier)modifier
- type:(NSPredicateOperatorType)type
- options:(NSUInteger)options
- enum{
- NSLessThanPredicateOperatorType=0,
- NSLessThanOrEqualToPredicateOperatorType,
- NSGreaterThanPredicateOperatorType,
- NSGreaterThanOrEqualToPredicateOperatorType,
- NSEqualToPredicateOperatorType,
- NSNotEqualToPredicateOperatorType,
- NSMatchesPredicateOperatorType,
- NSLikePredicateOperatorType,
- NSBeginsWithPredicateOperatorType,
- NSEndsWithPredicateOperatorType,
- NSInPredicateOperatorType,
- NSCustomSelectorPredicateOperatorType,
- NSContainsPredicateOperatorType,
- NSBetweenPredicateOperatorType
- };
- typedefNSUIntegerNSPredicateOperatorType;
- NSPredicate*shortNamePredicate=[NSPredicatepredicateWithBlock:^BOOL(idevaluatedObject,NSDictionary*bindings){
- return[[evaluatedObjectfirstName]length]<=5;
- }];
- //["AliceSmith","BobJones"]
- NSLog(@"ShortNames:%@",[peoplefilteredArrayUsingPredicate:shortNamePredicate]);
-(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]; } -(BOOL) isValidateMobile:(NSString *)mobile { //手机号以13, 15,18开头,八个 \d 数字字符 NSString *phoneRegex = @"^((13[0-9])|(15[^4,\\D])|(18[0,0-9]))\\d{8}$"; NSPredicate *phoneTest = [NSPredicate predicateWithFormat:@"SELF MATCHES %@",phoneRegex]; // NSLog(@"phoneTest is %@",phoneTest); return [phoneTest evaluateWithObject:mobile]; } BOOL validateCarNo(NSString* carNo) { NSString *carRegex = @"^[A-Za-z]{1}[A-Za-z_0-9]{5}$"; NSPredicate *carTest = [NSPredicate predicateWithFormat:@"SELF MATCHES %@",carRegex]; NSLog(@"carTest is %@",carTest); return [carTest evaluateWithObject:carNo]; }
NSString *searchText = @"// Do any additional setup after loading the view, typically from a nib.";
NSRange range = [searchText rangeOfString:@"(?:[^,])*\\." options:NSRegularExpressionSearch];
if (range.location != NSNotFound) {
NSLog(@"%@", [searchText substringWithRange:range]);
}
options中设定NSRegularExpressionSearch就是表示利用正则表达式匹配,会返回第一个匹配结果的位置。
3.使用正则表达式类
NSString *searchText = @"// Do any additional setup after loading the view, typically from a nib.";
NSError *error = NULL;
NSRegularExpression *regex = [NSRegularExpression regularExpressionWithPattern:@"(?:[^,])*\\." options:NSRegularExpressionCaseInsensitive error:&error];
NSTextCheckingResult *result = [regex firstMatchInString:searchText options:0 range:NSMakeRange(0, [searchText length])];
if (result) {
NSLog(@"%@\n", [searchText substringWithRange:result.range]);
}