释放双眼，带上耳机，听听看~！
-(BOOL)textField:(UITextField *)textField shouldChangeCharactersInRange:(NSRange)range replacementString:(NSString *)string{
NSString *temp = [[string componentsSeparatedByCharactersInSet:[NSCharacterSet whitespaceCharacterSet]]componentsJoinedByString:@""];
if (![string isEqualToString:temp]) {
return NO;
}
return YES;
}