NSPredicate

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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。

定义(最常用到的方法)：

NSPredicate *ca = [NSPredicate predicateWithFormat:(NSString *), ...];

Format：
(1)比较运算符>,<,==,>=,<=,!=
可用于数值及字符串
例：@"number > 100"

(2)范围运算符：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*'" //*代表通配符,Like也接受[cd].
@"name LIKE[cd] '???er*'"

(6)正则表达式：MATCHES
例：NSString *regex = @"^A.+e$"; //以A开头，e结尾
@"name MATCHES %@",regex

实际应用：
(1)对NSArray进行过滤

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)判断字符串首字母是否为字母:

NSString *regex = @"[A-Za-z]+";  NSPredicate *predicate = [NSPredicate predicateWithFormat:@"SELF MATCHES %@", regex];    if ([predicate evaluateWithObject:aString]) {  }

(3)字符串替换：

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：

//组装一个字符串，需要把里面的网址解析出来  NSString *urlString=@"<meta/><link/><title>1Q84 BOOK1</title></head><body>";    //NSRegularExpression类里面调用表达的方法需要传递一个NSError的参数。下面定义一个    NSError *error;    //http+:[^\\s]* 这个表达式是检测一个网址的。(?<=title\>).*(?=</title)截取html文章中的<title></title>中内文字的正则表达式  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];                    //从urlString当中截取数据          NSString *result=[urlString substringWithRange:resultRange];          //输出结果          NSLog(@"->%@<-",result);      }        }

(5)判断手机号码，电话号码函数

// 正则判断手机号码地址格式- (BOOL)isMobileNumber:(NSString *)mobileNum{       /**        * 手机号码        * 移动：134[0-8],135,136,137,138,139,150,151,157,158,159,182,187,188        * 联通：130,131,132,152,155,156,185,186        * 电信：133,1349,153,180,189        */       NSString * MOBILE = @"^1(3[0-9]|5[0-35-9]|8[025-9])\\d{8}$";       /**        10         * 中国移动：China Mobile        11         * 134[0-8],135,136,137,138,139,150,151,157,158,159,182,187,188        12         */       NSString * CM = @"^1(34[0-8]|(3[5-9]|5[017-9]|8[278])\\d)\\d{7}$";       /**        15         * 中国联通：China Unicom        16         * 130,131,132,152,155,156,185,186        17         */       NSString * CU = @"^1(3[0-2]|5[256]|8[56])\\d{8}$";       /**        20         * 中国电信：China Telecom        21         * 133,1349,153,180,189        22         */       NSString * CT = @"^1((33|53|8[09])[0-9]|349)\\d{7}$";       /**        25         * 大陆地区固话及小灵通        26         * 区号：010,020,021,022,023,024,025,027,028,029        27         * 号码：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)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;}

(7)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];