簡述：Cocoa架構中的NSPredicate用於查詢，原理和用法都類似於SQL中的where，作用相當於資料庫的過濾取。
最常用到的函數
+ (NSPredicate *)predicateWithFormat:(NSString *)predicateFormat, ...;
1.比較子 > 、< 、== 、 >= 、<= 、 !=
例：@"number >= 99"
2.範圍運算子：IN 、BETWEEN
例：@"number BETWEEN {1,5}"
@"address IN {'shanghai','nanjing'}"
3.字串本身:SELF
例：@"SELF == 'APPLE'"
4.字串相關：BEGINSWITH、ENDSWITH、CONTAINS
例：@"name CONTAIN[cd] 'ang'" //包含某個字串
@"name BEGINSWITH[c] 'sh'" //以某個字串開頭
@"name ENDSWITH[d] 'ang'" //以某個字串結束
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。
5.萬用字元：LIKE
例：@"name LIKE[cd] '*er*'" //*代表萬用字元,Like也接受[cd].
@"name LIKE[cd] '???er*'"
6.Regex：MATCHES
例：NSString *regex = @"^A.+e$"; //以A開頭，e結尾
@"name MATCHES %@",regex
實際應用:對NSArray進行過濾
NSArray *array = [[NSArray alloc]initWithObjects:@"beijing",@"shanghai",@"guangzou",@"wuhan", nil]; NSString *string = @"ang"; NSPredicate *pred = [NSPredicate predicateWithFormat:@"SELF CONTAINS %@",string]; NSLog(@"%@",[array filteredArrayUsingPredicate:pred]);
實際應用:判斷字串首字母是否為字母
NSString *regex = @"[A-Za-z]+"; NSPredicate *predicate = [NSPredicate predicateWithFormat:@"SELF MATCHES %@", regex]; if ([predicate evaluateWithObject:aString]) { }
實際應用:字串替換
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$2"]; NSLog(@"Result:%@", result);
實際應用:截取字串
//組裝一個字串，需要把裡面的網址解析出來 NSString *urlString=@"<meta/><link/><title>1Q84 BOOK1</title></head><body>"; //NSRegularExpression類裡面調用表達的方法需要傳遞一個NSError的參數。下面定義一個 NSError *error; //http+:[^\\s]* 這個運算式是檢測一個網址的。(?<=title\>).*(?=</title)截取html文章中的<title></title>中內文字的Regex NSRegularExpression *regex = [NSRegularExpression regularExpressionWithPattern:@"(?<=title\\>).*(?=</title)" options:0 error:&error]; if (regex != nil) { NSTextCheckingResult *firstMatch=[regex firstMatchInString:urlString options:0 range:NSMakeRange(0, [urlString length])]; if (firstMatch) { NSRange resultRange = [firstMatch rangeAtIndex:0]; //從urlString當中截取資料 NSString *result=[urlString substringWithRange:resultRange]; //輸出結果 NSLog(@"->%@<-",result); } }
實際應用:判斷手機號碼，電話號碼函數
// 正則判斷手機號碼地址格式- (BOOL)isMobileNumber:(NSString *)mobileNum{ /** * 手機號碼 * 移動：134[0-8],135,136,137,138,139,150,151,157,158,159,182,187,188 * 聯通：130,131,132,152,155,156,185,186 * 電信：133,1349,153,180,189 */ NSString * MOBILE = @"^1(3[0-9]|5[0-35-9]|8[025-9])\\d{8}$"; /** 10 * 中國移動：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}$"; /** 15 * 中國聯通：China Unicom 16 * 130,131,132,152,155,156,185,186 17 */ NSString * CU = @"^1(3[0-2]|5[256]|8[56])\\d{8}$"; /** 20 * 中國電信：China Telecom 21 * 133,1349,153,180,189 22 */ NSString * CT = @"^1((33|53|8[09])[0-9]|349)\\d{7}$"; /** 25 * 大陸地區固話及小靈通 26 * 區號：010,020,021,022,023,024,025,027,028,029 27 * 號碼：七位或八位 28 */ // NSString * PHS = @"^0(10|2[0-5789]|\\d{3})\\d{7,8}$"; 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; }}
實際應用:郵箱驗證、電話號碼驗證
//是否是有效Regex+(BOOL)isValidateRegularExpression:(NSString *)strDestination byExpression:(NSString *)strExpression{ NSPredicate *predicate = [NSPredicatepredicateWithFormat:@"SELF MATCHES %@", strExpression]; return [predicate evaluateWithObject:strDestination];}//驗證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;}//驗證電話號碼+(BOOL)isValidateTelNumber:(NSString *)number { NSString *strRegex = @"[0-9]{1,20}"; BOOL rt = [CommonTools isValidateRegularExpression:number byExpression:strRegex]; return rt;}
實際應用:NSDate進行篩選
//日期在十天之內:NSDate *endDate = [[NSDate date] retain];NSTimeInterval timeInterval= [endDate timeIntervalSinceReferenceDate];timeInterval -=3600*24*10;NSDate *beginDate = [[NSDate dateWithTimeIntervalSinceReferenceDate:timeInterval] retain];//對coredata進行篩選(假設有fetchRequest)NSPredicate *predicate_date =[NSPredicate predicateWithFormat:@"date >= %@ AND date <= %@", beginDate,endDate]; [fetchRequest setPredicate:predicate_date];//釋放retained的對象[endDate release];[beginDate release];
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