在iOS中衬浑，點擊textfield控件會彈出系統(tǒng)鍵盤昔脯，如果鍵盤位置在下方啄糙，那么會出現(xiàn)該控件被鍵盤遮擋的情況，這時候就需要讓textfield的位置隨著鍵盤彈出而變換云稚。研究了一下關(guān)鍵代碼如下隧饼。

- (void)viewWillAppear:(BOOL)animated {
    [super viewWillAppear:animated];
    [[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(keyBoardDidShow:) name:UIKeyboardDidShowNotification object:nil];
    [[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(keyBoardDidHide:) name:UIKeyboardDidHideNotification object:nil];
}

- (void)viewWillDisappear:(BOOL)animated {
    [super viewWillDisappear:animated];
    [[NSNotificationCenter defaultCenter] removeObserver:self name:UIKeyboardDidShowNotification object:nil];
    [[NSNotificationCenter defaultCenter] removeObserver:self name:UIKeyboardDidHideNotification object:nil];
}

- (void)keyBoardDidShow:(NSNotification *)notif {
    NSLog(@"===keyboar showed====");
    if (keyboardDidShow) return;
//    get keyboard size
    NSDictionary *info = [notif userInfo];
    NSValue *aValue = [info objectForKey:UIKeyboardFrameEndUserInfoKey];
    CGSize keyboardSize = [aValue CGRectValue].size;
    
//  reset scrollview frame
    CGRect viewFrame = self.scrollView.frame;
    viewFrame.size.height -= keyboardSize.height;
    self.scrollView.frame = viewFrame;
    
//    scroll to current textfiled
    CGRect textfieldRect = [self.textfield frame];
    [self.scrollView scrollRectToVisible:textfieldRect animated:YES];
    keyboardDidShow = YES;
    
}

- (void)keyBoardDidHide:(NSNotification *)notif {
    NSLog(@"====keyboard hidden====");
    NSDictionary *info = [notif userInfo];
    NSValue *aValue = [info objectForKey:UIKeyboardFrameEndUserInfoKey];
    CGSize keyboardSize = [aValue CGRectValue].size;
    CGRect viewFrame = self.scrollView.frame;
    viewFrame.size.height += keyboardSize.height;
    self.scrollView.frame = viewFrame;
    if (!keyboardDidShow) {
        return;
    }
    keyboardDidShow = NO;
}

@end

對代碼的解釋：
UIKeyboardDidShowNotification，UIKeyboardDidHideNotification分別是鍵盤出現(xiàn)和鍵盤消失的通知静陈。將ScrollView滾動到textfield控件燕雁，通過scrollRectToVisible:animated:來實現(xiàn)诞丽，其中scrollRectToVisible參數(shù)用于指定滾動到一個矩形區(qū)域，文檔中解釋為：Scrolls a specific area of the content so that it is visible in the receiver.這個矩形區(qū)域是CGRect結(jié)構(gòu)體拐格。每個視圖的frame方法可以獲得CGRrect結(jié)構(gòu)體數(shù)據(jù)僧免。