簡述:Cocoa框架中的NSPredicate用於查詢,原理和用法都相似於SQL中的where,做用至關於數據庫的過濾取。html
定義(最經常使用到的方法):正則表達式
- NSPredicate *ca = [NSPredicate predicateWithFormat:(NSString *), ...];
Format:
(1)比較運算符>,<,==,>=,<=,!=
可用於數值及字符串
例:@"number > 100"
(2)範圍運算符:IN、BETWEEN
例:@"number BETWEEN {1,5}"
@"address IN {'shanghai','beijing'}"
(3)字符串自己:SELF
例:@「SELF == ‘APPLE’"
(4)字符串相關:BEGINSWITH、ENDSWITH、CONTAINS
例:@"name CONTAIN[cd] 'ang'" //包含某個字符串
@"name BEGINSWITH[c] 'sh'" //以某個字符串開頭
@"name ENDSWITH[d] 'ang'" //以某個字符串結束
注:[c]不區分大小寫[d]不區分發音符號即沒有重音符號[cd]既不區分大小寫,也不區分發音符號。
(5)通配符:LIKE
例:@"name LIKE[cd] '*er*'" //*表明通配符,Like也接受[cd].
@"name LIKE[cd] '???er*'"數據庫
(6)正則表達式:MATCHES
例:NSString *regex = @"^A.+e$"; //以A開頭,e結尾
@"name MATCHES %@",regexxcode
實際應用:
(1)對NSArray進行過濾框架
- NSArray *array = [[NSArray alloc]initWithObjects:@"beijing",@"shanghai",@"guangzou",@"wuhan", nil nil];
- NSString *string = @"ang";
- NSPredicate *pred = [NSPredicate predicateWithFormat:@"SELF CONTAINS %@",string];
- NSLog(@"%@",[array filteredArrayUsingPredicate:pred]);
(2)判斷字符串首字母是否爲字母:函數
- NSString *regex = @"[A-Za-z]+";
- NSPredicate *predicate = [NSPredicate predicateWithFormat:@"SELF MATCHES %@", regex];
-
- if ([predicate evaluateWithObject:aString]) {
- }
(3)字符串替換:fetch
- 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$2"];
- NSLog(@"Result:%@", result);
(4)截取字符串:lua
- NSString *urlString=@"<meta/><link/><title>1Q84 BOOK1</title></head><body>";
-
- NSError *error;
-
- NSRegularExpression *regex = [NSRegularExpression regularExpressionWithPattern:@"(?<=title\\>).*(?=</title)" options:0 error:&error];
-
- if (regex != nil) {
- NSTextCheckingResult *firstMatch=[regex firstMatchInString:urlString options:0 range:NSMakeRange(0, [urlString length])];
-
- if (firstMatch) {
- NSRange resultRange = [firstMatch rangeAtIndex:0];
-
-
- NSString *result=[urlString substringWithRange:resultRange];
-
- NSLog(@"->%@<-",result);
- }
-
- }
(5)判斷手機號碼,電話號碼函數 url
- - (BOOL)isMobileNumber:(NSString *)mobileNum
- {
-
- NSString * MOBILE = @"^1(3[0-9]|5[0-35-9]|8[025-9])\\d{8}$";
-
- NSString * CM = @"^1(34[0-8]|(3[5-9]|5[017-9]|8[278])\\d)\\d{7}$";
-
- NSString * CU = @"^1(3[0-2]|5[256]|8[56])\\d{8}$";
-
- NSString * CT = @"^1((33|53|8[09])[0-9]|349)\\d{7}$";
-
-
-
- NSPredicate *regextestmobile = [NSPredicate predicateWithFormat:@"SELF MATCHES %@", MOBILE];
- NSPredicate *regextestcm = [NSPredicate predicateWithFormat:@"SELF MATCHES %@", CM];
- NSPredicate *regextestcu = [NSPredicate predicateWithFormat:@"SELF MATCHES %@", CU];
- NSPredicate *regextestct = [NSPredicate predicateWithFormat:@"SELF MATCHES %@", CT];
-
- if (([regextestmobile evaluateWithObject:mobileNum] == YES)
- || ([regextestcm evaluateWithObject:mobileNum] == YES)
- || ([regextestct evaluateWithObject: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;
- }
- }
(6)郵箱驗證、電話號碼驗證:spa
-
- +(BOOL)isValidateRegularExpression:(NSString *)strDestination byExpression:(NSString *)strExpression
-
- {
-
- NSPredicate *predicate = [NSPredicatepredicateWithFormat:@"SELF MATCHES %@", strExpression];
-
- return [predicate evaluateWithObject:strDestination];
-
- }
-
- +(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;
-
- }
-
- +(BOOL)isValidateTelNumber:(NSString *)number {
-
- NSString *strRegex = @"[0-9]{1,20}";
-
- BOOL rt = [CommonTools isValidateRegularExpression:number byExpression:strRegex];
-
- return rt;
-
- }
(7)NSDate進行篩選
- NSDate *endDate = [[NSDate date] retain];
- NSTimeInterval timeInterval= [endDate timeIntervalSinceReferenceDate];
- timeInterval -=3600*24*10;
- NSDate *beginDate = [[NSDate dateWithTimeIntervalSinceReferenceDate:timeInterval] retain];
- NSPredicate *predicate_date =
- [NSPredicate predicateWithFormat:@"date >= %@ AND date <= %@", beginDate,endDate];
-
- [fetchRequest setPredicate:predicate_date];
- [endDate release];
- [beginDate release];