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 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$2"];
- NSLog(@"Result:%@", result);
(4)截取字符串：
- //组装一个字符串，需要把里面的网址解析出来
- NSString *urlString=@"<meta/><link/><title>1Q84 BOOK1</title></head><body>";
- //NSRegularExpression类里面调用表达的方法需要传递一个NSError的参数。下面定义一个
- NSError *error;
- //http+:[^\\s]* 这个表达式是检测一个网址的。(?<=title\>).*(?=</title)截取html文章中的<title></title>中内文字的正则表达式
- NSRegularExpression *regex = [NSRegularExpression regularExpressionWithPattern:@"(?<=title\\>).*(?=</title)" options:0 error:&error];
- if (regex != nil) {
- NSTextCheckingResult *firstMatch=[regex firstMatchInString:urlString options:0 range:NSMakeRange(0, [urlString length])];
- if (firstMatch) {
- NSRange resultRange = [firstMatch rangeAtIndex:0];
- //从urlString当中截取数据
- NSString *result=[urlString substringWithRange:resultRange];
- //输出结果
- NSLog(@"->%@<-",result);
- }
- }
(5)判断手机号码，电话号码函数
- // 正则判断手机号码地址格式
- - (BOOL)isMobileNumber:(NSString *)mobileNum
- {
- /**
- * 手机号码
- * 移动：134[0-8],135,136,137,138,139,150,151,157,158,159,182,187,188
- * 联通：130,131,132,152,155,156,185,186
- * 电信：133,1349,153,180,189
- */
- NSString * MOBILE = @"^1(3[0-9]|5[0-35-9]|8[025-9])\\d{8}$";
- /**
- * 中国移动：China Mobile
- * 134[0-8],135,136,137,138,139,150,151,157,158,159,182,187,188
- */
- NSString * CM = @"^1(34[0-8]|(3[5-9]|5[017-9]|8[278])\\d)\\d{7}$";
- /**
- * 中国联通：China Unicom
- * 130,131,132,152,155,156,185,186
- */
- NSString * CU = @"^1(3[0-2]|5[256]|8[56])\\d{8}$";
- /**
- * 中国电信：China Telecom
- * 133,1349,153,180,189
- */
- NSString * CT = @"^1((33|53|8[09])[0-9]|349)\\d{7}$";
- /**
- * 大陆地区固话及小灵通
- * 区号：010,020,021,022,023,024,025,027,028,029
- * 号码：七位或八位
- */
- // NSString * PHS = @"^0(10|2[0-5789]|\\d{3})\\d{7,8}$";
- 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];
