簡述：Cocoa框架中的NSPredicate用于查詢，原理和用法都類似于SQL中的where，作用相當于數據庫的過濾取。
定義(最常用到的方法)：
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NSPredicate *ca = [NSPredicate predicateWithFormat:(NSString *), ...];
Format：(1)比較運算符>,<,==,>=,<=,!=可用于數值及字符串例：@"number > 100"(2)范圍運算符：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'" //代表通配符,Like也接受[cd]. @"name LIKE[cd] '???er'"
(6)正則表達式：MATCHES例：NSString *regex = @"^A.+e$"; //以A開頭，e結尾 @"name MATCHES %@",regex
實際應用：(1)對NSArray進行過濾
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NSArray *array = [[NSArray alloc]initWithObjects:@"beijing",@"shanghai",@"guangzou",@"wuhan", 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為字母:
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NSString *regex = @"[A-Za-z]+";
NSPredicate *predicate = [NSPredicate predicateWithFormat:@"SELF MATCHES %@", regex];
if ([predicate evaluateWithObject:aString]) {
}
(3)字符串替換：
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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$2"];
NSLog(@"Result:%@", result);
(4)截取字符串如下：
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//組裝一個字符串，需要把里面的網址解析出來
NSString *urlString=@"<meta/><link/><title>1Q84 BOOK1</title></head><body>";
//NSRegularExpression類里面調用表達的方法需要傳遞一個NSError的參數。下面定義一個
NSError *error;
//http+:[^\s]* 這個表達式是檢測一個網址的。(?<=title>).*(?=</title)截取html文章中的<title></title>中內文字的正則表達式
NSRegularExpression regex = [NSRegularExpression regularExpressionWithPattern:@"(?<=title\>).(?=</title)" options:0 error:&error];
if (regex != nil) {
NSTextCheckingResult *firstMatch=[regex firstMatchInString:urlString options:0 range:NSMakeRange(0, [urlString length])];
if (firstMatch) {
NSRange resultRange = [firstMatch rangeAtIndex:0];
//從urlString當中截取數據
NSString *result=[urlString substringWithRange:resultRange];
//輸出結果
NSLog(@"->%@<-",result);
}
}
(5)判斷手機號碼，電話號碼函數
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// 正則判斷手機號碼地址格式
-
(BOOL)isMobileNumber:(NSString )mobileNum
{
/*
* 手機號碼
* 移動：134[0-8],135,136,137,138,139,150,151,157,158,159,182,187,188
* 聯通：130,131,132,152,155,156,185,186
* 電信：133,1349,153,180,189
/
NSString * MOBILE = @"^1(3[0-9]|5[0-35-9]|8[025-9])\d{8}$";
/*
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;
}
}
(6)郵箱驗證、電話號碼驗證:
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//是否是有效的正則表達式
+(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;
}
(7)NSDate進行篩選
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//日期在十天之內:
NSDate endDate = [[NSDate date] retain];
NSTimeInterval timeInterval= [endDate timeIntervalSinceReferenceDate];
timeInterval -=360024*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];
