/**
* 功能: 判断长度大于6位小于20位并是否同时包含且只有数字和字母
*/
+(BOOL)judgePassWordLegal:(NSString *)text{
BOOL result = false;
if ([text length] >= 6){
NSString * regex = @"^(?![0-9]+$)(?![a-zA-Z]+$)[0-9A-Za-z]{6,20}$";
NSPredicate *pred = [NSPredicate predicateWithFormat:@"SELF MATCHES %@", regex];
result = [pred evaluateWithObject:text];
}
return result;
}