1. 对NSArray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-Z]+$";
    NSString *string = @"AdddadADa";
    NSPredicate *predicate = [NSPredicate predicateWithFormat:@"SELF MATCHES %@", regex];
    NSString *stringS = [string substringToIndex:1];
    
    NSLog(@"打印 == %@ %d",stringS,[predicate evaluateWithObject:stringS]);

3)各种验证

//1.0 正则验证(通用) regex 正则表达式 返回值：验证结果
- (BOOL)regular:(NSString *)regex {
    NSPredicate *predicateRe = [NSPredicate predicateWithFormat:@"self matches %@", regex];
    return [predicateRe evaluateWithObject:self];
}

//1.1 验证电话号码
- (BOOL)checkTelephoneNumber {
    NSString *regex = @"^1[3|4|5|7|8][0-9]\\d{8}$";
    NSPredicate *predicateRe = [NSPredicate predicateWithFormat:@"self matches %@", regex];
    return [predicateRe evaluateWithObject:self];
}

//1.2 验证身份证
- (BOOL)checkIDCard {
    NSString *regex = @"\\d{15}(\\d\\d[0-9xX])?";
    NSPredicate *predicateRe = [NSPredicate predicateWithFormat:@"self matches %@", regex];
    return [predicateRe evaluateWithObject:self];
}

//1.3 验证邮箱
- (BOOL)checkEmail {
    NSString *regex = @"^\\w+([-+.]\\w+)*@\\w+([-.]\\w+)*\\.\\w+([-.]\\w+)*$";
    NSPredicate *predicateRe = [NSPredicate predicateWithFormat:@"self matches %@", regex];
    return [predicateRe evaluateWithObject:self];
}

//1.4 验证纯数字
- (BOOL)checkJustNumber {
    NSString *regex = @"^[0-9]+$";
    NSPredicate *predicateRe = [NSPredicate predicateWithFormat:@"self matches %@", regex];
    return [predicateRe evaluateWithObject:self];
}

//1.5 验证URL
- (BOOL)checkURL {
    NSString *regex = @"^http(s)?://([\\w-]+\\.)+[\\w-]+(/[\\w-./?%&=]*)?$";
    NSPredicate *predicateRe = [NSPredicate predicateWithFormat:@"self matches %@", regex];
    return [predicateRe evaluateWithObject:self];
}

//1.6 验证只是汉字
- (BOOL)checkJustChinese {
    NSString *regex = @"^[\u4e00-\u9fa5]+$";
    NSPredicate *predicateRe = [NSPredicate predicateWithFormat:@"self matches %@", regex];
    return [predicateRe evaluateWithObject:self];
}

//1.7 验证只是字母
- (BOOL)checkJustLetter {
    NSString *regex = @"^[A-Za-z]+$";
    NSPredicate *predicateRe = [NSPredicate predicateWithFormat:@"self matches %@", regex];
    return [predicateRe evaluateWithObject:self];
}

//1.8 验证只是小写字母
- (BOOL)checkJustLowercase {
    NSString *regex = @"^[a-z]+$";
    NSPredicate *predicateRe = [NSPredicate predicateWithFormat:@"self matches %@", regex];
    return [predicateRe evaluateWithObject:self];
}

//1.9 验证只是大写字母
- (BOOL)checkCapitalLetter {
    NSString *regex = @"^[A-Z]+$";
    NSPredicate *predicateRe = [NSPredicate predicateWithFormat:@"self matches %@", regex];
    return [predicateRe evaluateWithObject:self];
}

//1.10 验证包含特殊字符
- (BOOL)checkContainSpecialCharacter {
    NSString *regex = @"[~`!@#$%^&*':;\"\?=/<>,\\.\\{\\}\\[\\]\\(\\)]+";
    NSPredicate *predicateRe = [NSPredicate predicateWithFormat:@"self matches %@", regex];
    return [predicateRe evaluateWithObject:self];
}