UITextField一些常用屬性和方法

//成爲第一響應者  -- becomeFirstResponder

[self.numberField becomeFirstResponder];

//取消第一響應者  — resignFirstResponder

[self.numberField resignFirstResponder];

//取消編輯
[self.view endEditing:YES];

textField.secureTextEntry = YES; //以密碼樣式顯示

//是否要清楚view顯示以後選中狀態
self.clearsSelectionOnViewWillAppear = NO;

// 告訴tableView是否允許編輯
- (BOOL)tableView:(UITableView*)tableView canEditRowAtIndexPath:(NSIndexPath*)indexPath
{
    // Return NO if you do not want the specified item to be editable.
    return YES;
}

限制文本框只能輸入數字:

//建立NSNumberFormatter的子類，增加這個方法，將formatter鏈接至文本框。

- (BOOL) isPartialStringValid: (NSString **) partialStringPtr
        proposedSelectedRange: (NSRangePointer) proposedSelRangePtr
               originalString: (NSString *) origString
        originalSelectedRange: (NSRange) origSelRange
             errorDescription: (NSString **) error
{
    NSCharacterSet *nonDigits;
    NSRange newStuff;
    NSString *newStuffString;

    nonDigits = [[NSCharacterSet decimalDigitCharacterSet] invertedSet];
    newStuff = NSMakeRange(origSelRange.location,
                           proposedSelRangePtr->location
                           - origSelRange.location);
    newStuffString = [*partialStringPtr substringWithRange: newStuff];

    if ([newStuffString rangeOfCharacterFromSet: nonDigits
                                                                                             options: NSLiteralSearch].location != NSNotFound) {
        *error = @"不是數字";
        return (NO);
    } else {
        *error = nil;
        return (YES);
    }

}