首先舉一個例子：
匹配9-15個由字母/數字組成的字符串的正則表達式：
? ? 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，原理類似于在數據庫中進行查詢

用BETWEEN，IN，BEGINWITH，ENDWITH，CONTAINS，LIKE這些謂詞來構造NSPredicate，必要的時候使用SELF直接對自己進行匹配

[cpp]?view plaincopy

//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cars里面循環比較??

????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，因為它值代表值??

//謂詞字符竄還支持c語言中一些常用的運算符??

?????

????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"]);??

//強大的數組運算符??

????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，[c],[d],[cd],c表示不區分大小寫，d表示不區分發音字符，cd表示什么都不區分??

????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); ?

NSPredicate用于查詢和過濾

在SQL中作為查詢條件通常用WHERE，但在COREDATA中作為查詢條件就可以用到NSPredicate.

NSPredicate 不單可以和COREDATA中的FetchRequest 配合使用。也可以與NSArray配合使用。

?

NSPredicate 中支持的關鍵詞和條件符：

1、>,<,>=,<=,= 比較運算符。

如：

???? NSPredicate * qcondition= [NSPredicate predicateWithFormat:@"salary >= 10000"];

2、字符串操作(包含)：BEGINSWITH、ENDSWITH、CONTAINS

如：

????????@"employee.name BEGINSWITH[cd] '李'" //姓李的員工

???? @"employee.name ENDSWITH[c] '夢'"?? //以夢結束的員工

???? @"employee.name CONTAINS[d] '宗'"?? //包含有"宗"字的員工

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。

?

3、范圍：IN?? ，BWTEEN

如：

??? @"salary BWTEEN {5000,10000}"

??? @"em_dept IN '開發'"

?

4、自身:SELF，這個只針對字符數組起作用。

如：

???? NSArray * test = =[NSArray arrayWithObjects: @"guangzhou", @"beijing", @"shanghai", nil];

???? @"SELF='beijing'"

?

5、通配符：LIKE

???? LIKE 使用?表示一個字符，*表示多個字符，也可以與c、d 連用。

如：

???? @"car.name LIKE '?he?'" //四個字符中，中間為he

???? @"car.name LIKE '*jp'"?? //以jp結束

?

6、正則表達式：MATCHES

如：

NSString *regex = @"^E.+e$";//以E 開頭，以e 結尾的字符。
NSPredicate *pre= [NSPredicate predicateWithFormat:@"SELF MATCHES %@", regex];
if([pre evaluateWithObject: @"Employee"]){
NSLog(@"matches YES");

}else{
NSLog(@"matches NO");

}

?

7、邏輯運算符：AND、OR、NOT
如：

????? @"employee.name = 'john' AND employee.age = 28"

?

8、占位符：
NSPredicate *preTemplate = [NSPredicate predicateWithFormat:@"name==$NAME"];
NSDictionary *dic=[NSDictionary dictionaryWithObjectsAndKeys:
@"Name1", @"NAME",nil];
NSPredicate *pre=[preTemplate predicateWithSubstitutionVariables: dic];
占位符就是字典對象里的key，因此你可以有多個占位符，只要key 不一樣就可以了。

?

對數組過濾：

如：

?NSMutableArray?*carsCopy = [carsmutableCopy];

? ? [carsCopyfilterUsingPredicate: predicate];//filterUsingPredicate和NSMutableArray構成新數組。

? ??NSLog?(@"%@", carsCopy);

?? ?

? ? predicate = [NSPredicatepredicateWithFormat:@"engine.horsepower > %d",?50];

? ? results = [cars?filteredArrayUsingPredicate: predicate];

? ??NSLog?(@"%@", results);

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