ios 将 UITextView 滚动到底部

Scroll UITextView To Bottom

提问by Jonis

I am making a an app that has a UITextViewand a button.

我正在制作一个有一个UITextView和一个按钮的应用程序。

When I click the button some text will add in the UITextView.

当我单击按钮时，一些文本将添加到UITextView.

But when clicking the button, I wan't to scroll down to the bottom of the text field so the user can see the last text added.

但是当单击按钮时，我不想向下滚动到文本字段的底部，这样用户就可以看到最后添加的文本。

How to make the UITextViewto scroll down to the bottom?

如何使UITextView向下滚动到底部？

I tried:

我试过：

int numLines = LogTextView.contentSize.height / LogTextView.font.lineHeight+1;
NSLog(@"%d",numLines);

NSUInteger length = self.LogTextView.text.length;
self.LogTextView.selectedRange = NSMakeRange(0, length);

but it will not work...

但它不会工作......

I also tried:

我也试过：

self.LogTextView.contentSize=CGSizeMake(length,0);

回答by danypata

You can use the following code if you are talking about UITextView:

如果您正在谈论 UITextView，则可以使用以下代码：

-(void)scrollTextViewToBottom:(UITextView *)textView {
     if(textView.text.length > 0 ) {
        NSRange bottom = NSMakeRange(textView.text.length -1, 1);
        [textView scrollRangeToVisible:bottom];
     }

}

SWIFT 4:

快速 4：

func scrollTextViewToBottom(textView: UITextView) {
    if textView.text.count > 0 {
        let location = textView.text.count - 1
        let bottom = NSMakeRange(location, 1)
        textView.scrollRangeToVisible(bottom)
    }
}

回答by Hong Duan

Try this if you have problem on iOS 7 or above. See this SO answer.

如果您在 iOS 7 或更高版本上遇到问题，请尝试此操作。请参阅此 SO 答案。

- (void)scrollTextViewToBottom:(UITextView *)textView {
    NSRange range = NSMakeRange(textView.text.length, 0);
    [textView scrollRangeToVisible:range];
    // an iOS bug, see https://stackoverflow.com/a/20989956/971070
    [textView setScrollEnabled:NO];
    [textView setScrollEnabled:YES];
}

回答by zeeawan

With Swift 3

使用 Swift 3

let bottom = self.textView.contentSize.height - self.textView.bounds.size.height
self.textView.setContentOffset(CGPoint(x: 0, y: bottom), animated: true)

回答by wolffan

You have to implement a delegate method. The code below checks whether a newline has been entered and, if so, scrolls to the bottom of the textView:

你必须实现一个委托方法。下面的代码检查是否输入了换行符，如果是，则滚动到 textView 的底部：

- (BOOL)textView:(UITextView *)textView shouldChangeTextInRange:(NSRange)range replacementText:(NSString *)text
{

    if ([text isEqualToString:@"\n"]) {
        textView.contentOffset = CGPointMake(0.0, textView.contentSize.height);
    }
    return YES;
}

回答by Brandon Boynton

This works for me! :D

这对我有用！:D

CGPoint bottomOffset = CGPointMake(0, self.textView.contentSize.height - self.textView.bounds.size.height);
[self.description1 setContentOffset:bottomOffset animated:YES];

回答by Chris Amelinckx

Make a range, specifying encoding, to the last character, then scroll to that range Something other than utf8 might be appropriate depending on your content

创建一个范围，指定编码，到最后一个字符，然后滚动到该范围根据您的内容，utf8 以外的其他内容可能更合适

let range = NSMakeRange(self.OutputTextView.text.lengthOfBytes(using: String.Encoding.utf8), 0);
self.OutputTextView.scrollRangeToVisible(range);

回答by ArunGJ

As a generic approach for scrolling to bottom, it can be done on a UIScrollView.

作为滚动到底部的通用方法，它可以在 UIScrollView 上完成。

extension UIScrollView {
    func scrollToBottom() {
        let contentHeight = contentSize.height - frame.size.height
        let contentoffsetY = max(contentHeight, 0)
        setContentOffset(CGPoint(x: 0, y: contentoffsetY), animated: true)
    }
}

This will work on all descendants of UIScrollView like UITextView, UITableView etc..

这将适用于 UIScrollView 的所有后代，如 UITextView、UITableView 等。

回答by neoneye

Swift 4

斯威夫特 4

extension UITextView {
    func simple_scrollToBottom() {
        let textCount: Int = text.count
        guard textCount >= 1 else { return }
        scrollRangeToVisible(NSMakeRange(textCount - 1, 1))
    }
}

// Usage
textView.simple_scrollToBottom()

I wasn't able to find a solution without using NSRange.

我无法在不使用的情况下找到解决方案NSRange。

回答by Nathan Hosselton

textView.scrollRangeToVisible(NSRange(..<textView.text.endIndex, in: textView.text))

This solution does a couple of notable things slightly different:

这个解决方案做了几个值得注意的事情，略有不同：

• Utilizes the String.Indexinterface (likely more performant than e.g. .count)
• Uses a PartialRangeUpTowhich avoids an explicit range start position, reducing the code to a clean one-liner

• 利用String.Index接口（可能比 eg 性能更高.count）
• 使用 aPartialRangeUpTo避免明确的范围开始位置，将代码简化为干净的单行代码

回答by yoAlex5

The Swift version of @Hong Duan answer

@Hong Duan的 Swift 版回答

func scrollTextViewToBottom(textView: UITextView) {
    if textView.text.count > 0 {
        let location = textView.text.count - 1
        let bottom = NSMakeRange(location, 1)
        textView.scrollRangeToVisible(bottom)

        // an iOS bug, see https://stackoverflow.com/a/20989956/971070
        textView.isScrollEnabled = false
        textView.isScrollEnabled = true
    }
}