//对数组进行过滤

NSArray *array = [[NSArray alloc]initWithObjects:@"beijing",@"shanghai",@"guangzou",@"wuhan",nil];

NSString *string = @"ang";

NSPredicate *pred = [NSPredicate predicateWithFormat:@"SELF CONTAINS %@",string];

NSLog(@"%@",[array filteredArrayUsingPredicate:pred]);

//判断字符串是否为字母

NSString *regex = @"[A-Za-z]+";

NSPredicate *predicate = [NSPredicate predicateWithFormat:@"SELF MATCHES %@",regex];

NSString *aString=@"nkl";

if ([predicate evaluateWithObject:aString]) {

NSLog(@"是字母");

}else

{

NSLog(@"不是字母啊");

}