iOS学习之NSPredicate

Cocoa框架中的NSPredicate类一般用来，筛选查询字符串的匹配，原理和用法类似于SQL语句，作用相当于数据库的查询过滤读取。

NSPredicate初始化方法

NSPredicate *predicate = [NSPredicate predicateWithFormat:@"(lastName like[cd] %@) AND (birthday > %@)", lastNameSearchString, birthdaySearchDate];

你可以使用NSPredicate的类方法predicateWithFormat…来直接从一个字符串来创建一个实例对象，上面的谓词同时设置了两个约束查询条件。还有两种初始化方法，一个是直接创建，一个是通过predicate临时变量来创建。另外两种方法并不常用，这里不做过多介绍如需了解，可自行查看官方文档https://developer.apple.com/library/ios/documentation/Cocoa/Conceptual/Predicates/Articles/pCreating.html#//apple_ref/doc/uid/TP40001793-CJBDBHCB

Predicate常用的语法格式

• 比较运算符>,<,==,>=,<=,!=可用于数值及字符串。例：
  @"number > 100"
• 范围运算符：IN、BETWEEN。例：
  @"number BETWEEN {1,5}"
@"address IN {'shanghai','beijing'}"
• 字符串本身:SELF。例：
  @“SELF == ‘APPLE’"
• 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。
• 通配符：LIKE。例：
  @"name LIKE[cd] '*er*'" //*代表通配符,Like也接受[cd].
@"name LIKE[cd] '???er*'"
• 正则表达式：MATCHES。例：
  NSString *regex = @"^A.+e$"; //以A开头，e结尾
@"name MATCHES %@",regex

NSPredicate使用实例

• 对数组进行筛选

    // 筛选数组中的元素。
    // NSArray *array = [[NSArray alloc]initWithObjects:@"beijing",@"shanghai",@"guangzou",@"wuhan", nil];    
    // NSString *string = @"ang";    
    // NSPredicate *pred = [NSPredicate predicateWithFormat:@"SELF CONTAINS %@",string];    
    // NSLog(@"%@",[array filteredArrayUsingPredicate:pred]);
    // array的实例方法
    - (NSArray *)filterArrayWithString:(NSString *)string {
        NSPredicate *pred = [NSPredicate predicateWithFormat:@"SELF CONTAINS %@",string];    
        return [array filteredArrayUsingPredicate:pred];
    }
  

• 判断首个字符是否为字母

    // 判断首个字符是否为字母
    - (BOOL)isStartWithWord {
        NSString *regex = @"[A-Za-z]+";    
        NSPredicate *predicate = [NSPredicate predicateWithFormat:@"SELF MATCHES %@", regex];    
        return [predicate evaluateWithObject:aString];
    }
  

• 用户名是否为字母和数字组成

    - (BOOL)isUserName  
    {  
        NSString *regex = @"(^[A-Za-z0-9]{3,20}$)";  
        NSPredicate *pred = [NSPredicate predicateWithFormat:@"SELF MATCHES %@", regex];  
        
        return [pred evaluateWithObject:self];  
    } 
  

• 密码是否合法

    - (BOOL)isPassword  
    {  
        NSString *regex = @"(^[A-Za-z0-9]{6,20}$)";  
        NSPredicate *pred = [NSPredicate predicateWithFormat:@"SELF MATCHES %@", regex];  
        
        return [pred evaluateWithObject:self];    
    }  
  

• 邮箱是否合法

    - (BOOL)isEmail  
    {  
        NSString *regex = @"[A-Z0-9a-z._%+-]+@[A-Za-z0-9.-]+\\.[A-Za-z]{2,4}";  
        NSPredicate *pred = [NSPredicate predicateWithFormat:@"SELF MATCHES %@", regex];  
        
        return [pred evaluateWithObject:self];  
    }
  

• url是否合法

    - (BOOL)isUrl  
    {  
        NSString *regex = @"http(s)?:\\/\\/([\\w-]+\\.)+[\\w-]+(\\/[\\w- .\\/?%&=]*)?";  
        NSPredicate *pred = [NSPredicate predicateWithFormat:@"SELF MATCHES %@", regex];  
        
        return [pred evaluateWithObject:self];  
    } 
  

• 电话号码是否合法

    - (BOOL)isTelephone  
    {  
        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];  
        NSPredicate *regextestphs = [NSPredicate predicateWithFormat:@"SELF MATCHES %@", PHS];  
    
        return  [regextestmobile evaluateWithObject:self]   ||  
                [regextestphs evaluateWithObject:self]      ||  
                [regextestct evaluateWithObject:self]       ||  
                [regextestcu evaluateWithObject:self]       ||  
                [regextestcm evaluateWithObject:self];  
    }