xcode 4.2.1 - 限制 TextField 中的字符长度
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xcode 4.2.1 - limiting character length in TextField
提问by Jan
I have been trying to limit a textField by many codes available out there in the internet but with no luck.
我一直试图通过互联网上可用的许多代码来限制 textField ，但没有运气。
I have added UIViewController<UITextFieldDelegate>in my header file
我已经UIViewController<UITextFieldDelegate>在我的头文件中添加了
and textField.delegate = self;in my viewDidLoad
而textField.delegate = self;在我的viewDidLoad
and implemented the following fundtion in my .m file:
并在我的 .m 文件中实施了以下基金：
- (BOOL)textField:(UITextField *)textField shouldChangeCharactersInRange:(NSRange)range replacementString:(NSString *)string
{
NSString *newString = [textField.text stringByReplacingCharactersInRange:range withString:string];
return !([newString length] > 5);
}
this stil does not limit my text field. any idea?
这仍然不限制我的文本字段。任何的想法？
回答by Ilanchezhian
Do it as following as it has been the exact duplicate of this
请按照以下方式进行，因为它与此完全相同
- (BOOL)textField:(UITextField *)textField shouldChangeCharactersInRange:(NSRange)range replacementString:(NSString *)string {
NSUInteger newLength = [textField.text length] + [string length] - range.length;
return (newLength > 5) ? NO : YES;
}
回答by Darren
The replacement string is just the 1 character that was pressed, not the whole string so you need to add It to the current textfield.text before counting. Your count is probably always 1 (or more if pasting a word)
替换字符串只是被按下的 1 个字符，而不是整个字符串，因此您需要在计数之前将它添加到当前的 textfield.text 中。您的计数可能始终为 1（如果粘贴一个字则更多）
回答by Eduardo Iglesias
I implement this in my code and it works:
我在我的代码中实现了它并且它有效：
This code eliminate all the letters only accept numbers, but like I delete the character, you could delete everything that its over length 5 and it keeps a nice effect that appears and disappears
此代码消除所有字母只接受数字，但就像我删除字符一样，您可以删除长度超过 5 的所有内容，并保持出现和消失的良好效果
- (void)textFieldDidBeginEditing:(UITextField *)textField {
[[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(textChanged:) name:UITextFieldTextDidChangeNotification object:textField];
}
- (void)textChanged:(NSNotification *)textField {
NSString *text = [[textField object] text];
NSString *last = [text substringFromIndex:[text length] -1];
NSArray *accept = [NSArray arrayWithObjects:@"0", @"1", @"2", @"3", @"4", @"5", @"6", @"7" , @"8", @"9", @".", nil];
for (int i=0; i<[accept count]; i++) {
NSLog(@"%@", [accept objectAtIndex:i]);
if (![last isEqualToString:[accept objectAtIndex:i]]) {
[[textField object] setText:[text substringToIndex:[text length]-1]];
}
}
}
