Welcome to OGeek Q&A Community for programmer and developer-Open, Learning and Share
Welcome To Ask or Share your Answers For Others

Categories

0 votes
448 views
in Technique[技术] by (71.8m points)

ios7 - iOS 7.1 UITextView still not scrolling to cursor/caret after new line

Since iOS 7, a UITextView does not scroll automatically to the cursor as the user types text that flows to a new line. This issue is well documented on SO and elsewhere. For me, the issue is still present in iOS 7.1. What am I doing wrong?

enter image description here

I installed Xcode 5.1 and targeted iOS 7.1. I'm using Auto Layout.

Here's how I position the text view's content above the keyboard:

- (void)keyboardUp:(NSNotification *)notification
{
    NSDictionary *info = [notification userInfo];
    CGRect keyboardRect = [[info objectForKey:UIKeyboardFrameEndUserInfoKey] CGRectValue];
    keyboardRect = [self.view convertRect:keyboardRect fromView:nil];

    UIEdgeInsets contentInset = self.textView.contentInset;
    contentInset.bottom = keyboardRect.size.height;
    self.textView.contentInset = contentInset;
}

What I have tried: I have tried many of the solutions posted to SO on this issue as it pertains to iOS 7. All of the solutions that I have tried do not seem to hold up well for text views displaying an attributed string. In the following three steps, I outline how the most up-voted answer on SO (https://stackoverflow.com/a/19277383/1239263) responds to the user tapping the return key for the first time.

(1.) The text view became the first responder in viewDidLoad. Scroll to the bottom of the text view where the cursor is located.

enter image description here

(2.) Before typing a single character, tap the return key on the keyboard. The caret disappears out of sight.

enter image description here

(3.) Tapping the return key again, however, seems to normalize the situation. (Note: deleting the latter new line, however, makes the caret disappear once again).

enter image description here

See Question&Answers more detail:os

与恶龙缠斗过久,自身亦成为恶龙;凝视深渊过久,深渊将回以凝视…
Welcome To Ask or Share your Answers For Others

1 Reply

0 votes
by (71.8m points)

Improved solution's code for UITextView descendant class:

#define SYSTEM_VERSION_GREATER_THAN_OR_EQUAL_TO(v) ([[[UIDevice currentDevice] systemVersion] compare:v options:NSNumericSearch] != NSOrderedAscending)
#define is_iOS7 SYSTEM_VERSION_GREATER_THAN_OR_EQUAL_TO(@"7.0")
#define is_iOS8 SYSTEM_VERSION_GREATER_THAN_OR_EQUAL_TO(@"8.0")

@implementation MyTextView {
    BOOL settingText;
}

- (id)initWithFrame:(CGRect)frame {
    self = [super initWithFrame:frame];
    if (self) {
        [[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(handleTextViewDidChangeNotification:) name:UITextViewTextDidChangeNotification object:self];
    }
    return self;
}

- (void)scrollToCaretInTextView:(UITextView *)textView animated:(BOOL)animated {
    CGRect rect = [textView caretRectForPosition:textView.selectedTextRange.end];
    rect.size.height += textView.textContainerInset.bottom;
    [textView scrollRectToVisible:rect animated:animated];
}

- (void)handleTextViewDidChangeNotification:(NSNotification *)notification {
    if (notification.object == self && is_iOS7 && !is_iOS8 && !settingText) {
        UITextView *textView = self;
        if ([textView.text hasSuffix:@"
"]) {
            [CATransaction setCompletionBlock:^{
                [self scrollToCaretInTextView:textView animated:NO];
            }];
        } else {
            [self scrollToCaretInTextView:textView animated:NO];
        }
    }
}

- (void)setText:(NSString *)text {
    settingText = YES;
    [super setText:text];
    settingText = NO;
}

Note it doesn't work when Down key is pressed on Bluetooth keyboard.


与恶龙缠斗过久,自身亦成为恶龙;凝视深渊过久,深渊将回以凝视…
OGeek|极客中国-欢迎来到极客的世界,一个免费开放的程序员编程交流平台!开放,进步,分享!让技术改变生活,让极客改变未来! Welcome to OGeek Q&A Community for programmer and developer-Open, Learning and Share
Click Here to Ask a Question

...