如何检查字符串中是否只包含目标C中的字母数字字符？
问题描述：
我正在开发一个小型iphone项目，我需要检查输入的userName是否只包含字母数字字符？ （AZ，az，0-9 。我将如何检查？
I'm working on a small iphone project and i would need to check if the userName entered only contains alphanumerical characters? (A-Z, a-z, 0-9. How would i go about checking it?
答
如果您不想为这一项任务引入正则表达式库...
If you don't want to bring in a regex library for this one task...
NSString *str = @"aA09";
NSCharacterSet *alphaSet = [NSCharacterSet alphanumericCharacterSet];
BOOL valid = [[str stringByTrimmingCharactersInSet:alphaSet] isEqualToString:@""];