限制用户只在UITextField中输入一个单词

Question

是否有一种方法只允许用户在UITextField中输入一个单词？如果是这样，怎么样？

下面是我使用的当前代码：

-(BOOL) textField:(UITextField *)textField shouldChangeCharactersInRange:(NSRange)range replacementString:(NSString *)string{ 

_disallowedCharacters = [NSCharacterSet whitespaceCharacterSet]; 

for(int i = 0; i < [_searchBox.text length]; i++){ 
    unichar c = [_searchBox.text characterAtIndex:i]; 
    if (![_disallowedCharacters characterIsMember:c]) 
    { 
     return NO; 
    } 
} 
return YES; 
} 

Answer 1

使用UITextFieldDelegate协议：

- (BOOL) textField:(UITextField*)textField shouldChangeCharactersInRange:(NSRange)range replacementString:(NSString*)textEntered 
{ 
    for (int i = 0; i < [textEntered length]; i++) 
    { 
     unichar c = [textEntered characterAtIndex:i]; 
     if ([disallowedCharacters characterIsMember:c]) 
     { 
      return NO; 
     } 
    } 
    return YES; 
} 

其中disallowedCharacters是包含不应被键盘所接受的字符的NSCharacterSet，即空格，标点符号，数字等：

self.disallowedCharacters = [NSCharacterSet characterSetWithCharactersInString:@" ,.123"]; 

Answer 2

对于字符集（Evan的答案），检查对空格和换行，你可以使用

self.disallowedCharacters = [NSCharacterSet whitespaceAndNewlineCharacterSet]; 

如果你想核对除了空格和换行字符，创建一个mutableCopy并添加任何你想它：

NSMutableCharacterSet *set = [[NSCharacterSet whitespaceAndNewlineCharacterSet] mutableCopy]; 
[set formUnionWithCharacterSet:[NSCharacterSet punctuationCharacterSet]]; 
[set formUnionWithCharacterSet:[NSCharacterSet symbolCharacterSet]; 
[set addCharactersInString:@"whatever you want"]; 
... 
self.disallowedCharacters = [[set copy] autorelease]; 
[set release]; 

NSCharacterSet docs有一个很好的可用字符集的概述。