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。

最常用到的函数

+ (NSPredicate *)predicateWithFormat:(NSString *)predicateFormat, ...;

1.比较运算符 > 、< 、== 、 >= 、<= 、 !=
例：@"number >= 99"

2.范围运算符：IN 、BETWEEN
例：@"number BETWEEN {1,5}"
      @"address IN {'shanghai','nanjing'}"

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*'"    / 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}$"; NSString * CT = @"^1((33|53|8[09])[0-9]|349)\\d{7}$"; // 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; } }

实际应用:邮箱验证、电话号码验证

//是否是有效的正则表达式

+(BOOL)isValidateRegularExpression:(NSString *)strDestination byExpression:(NSString *)strExpression

{

   NSPredicate *predicate = [NSPredicatepredicateWithFormat:@"SELF MATCHES %@", strExpression];  

   return [predicate evaluateWithObject:strDestination];

}

//验证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;

}

//验证电话号码
+(BOOL)isValidateTelNumber:(NSString *)number {

   NSString *strRegex = @"[0-9]{1,20}";

   BOOL rt = [CommonTools isValidateRegularExpression:number byExpression:strRegex];

   return rt;

}

实际应用:NSDate进行筛选

//日期在十天之内:
NSDate *endDate = [[NSDate date] retain];
NSTimeInterval timeInterval= [endDate timeIntervalSinceReferenceDate];
timeInterval -=3600*24*10;
NSDate *beginDate = [[NSDate dateWithTimeIntervalSinceReferenceDate:timeInterval] retain];
//对coredata进行筛选(假设有fetchRequest)
NSPredicate *predicate_date =
[NSPredicate predicateWithFormat:@"date >= %@ AND date <= %@", beginDate,endDate];
    
[fetchRequest setPredicate:predicate_date];
//释放retained的对象
[endDate release];
[beginDate release];

原文地址：http://www.cnblogs.com/thefeelingofsimple/archive/2013/01/31/2886915.html