【iOS开发】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];

转载地址：NSPredicate

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