UIScrollView中的UITextView无法滚动-目标c

Question

I am trying to display a message with dynamic height using UITextView but when the message is long enough to cover the screen, I don't get the functionality of scrolling. I have tried many online solutions, but all failed. I use NSMutableAttributedString to format my text.

Here is my last attempt:

NSMutableAttributedString * attrStr = [[NSMutableAttributedString alloc] initWithData:[self.descString dataUsingEncoding:NSUTF8StringEncoding] options:@{ NSDocumentTypeDocumentAttribute: NSHTMLTextDocumentType } documentAttributes:nil error:nil];

    __block BOOL found = NO;
    [attrStr beginEditing];
    [attrStr enumerateAttribute:NSFontAttributeName inRange:NSMakeRange(0, attrStr.length) options:0 usingBlock:^(id value, NSRange range, BOOL *stop) {
        if (value) {
            UIFont *oldFont = (UIFont *)value;
            UIFont *newFont = [oldFont fontWithSize:16];
            [attrStr addAttribute:NSFontAttributeName value:newFont range:range];
            [attrStr addAttribute:NSForegroundColorAttributeName
                            value:[UIColor darkGrayColor]
                            range:range];

            found = YES;
        }
    }];
    if (!found) {
        // No font was found - do something else?
    }
    [attrStr endEditing];

CGRect labelSize = [attrStr boundingRectWithSize:CGSizeMake(self.view.frame.size.width, 10000) options:NSStringDrawingUsesLineFragmentOrigin | NSStringDrawingUsesFontLeading context:nil];



self.textviewHeight.constant = labelSize.size.height;

In Interface Builder I used a UIScrollView, inside it I placed a UIView and inside UIView I added a UITextView. textviewHeight is the height constraint of the UITextView. I can't believe that a simple thing like this took me so many hours and I still don't have a solution. Please help !

---

Other solutions I tried and failed:

1.

CGRect labelSize = [self.descString boundingRectWithSize:CGSizeMake(self.view.frame.size.width * 0.97, CGFLOAT_MAX) options:NSStringDrawingUsesLineFragmentOrigin attributes:@{NSFontAttributeName:[UIFont systemFontOfSize:15]} context:nil];

    self.descView.frame = CGRectMake(labelSize.origin.x,
                                    labelSize.origin.y,
                                    ceil(labelSize.size.width),
                                    ceil(labelSize.size.height));


    [self.descView sizeToFit];

2.

CGRect labelSize = [attrStr boundingRectWithSize:CGSizeMake(self.view.frame.size.width * 0.97, CGFLOAT_MAX) options:NSStringDrawingUsesLineFragmentOrigin | NSStringDrawingUsesFontLeading context:nil];

    CGRect frame = self.descView.frame;
    frame.size.height = labelSize.size.height;
    self.descView.frame = frame;

I don't mind using a UILabel if it's easier to implement.

Answer 1

If I understand what you're attempting to accomplish, you shouldn't need to do any programmatic height calculations.

My best guess is that you're setting the bottom constraint for the TextView (which is constraining it from scrolling it's complete contents).

Try putting the TextView as a subview of a standard UIView and set the leading/trailing/bottom/top constraints of that view (for the total area you want the TextView to be displayed in), then put the TextView within that and set the leading/trailing/top NOT BOTTOM (I'm assuming you want it to be able to scroll vertically) constraints, it will complain about no height/y constraint so go ahead and set the centerY equal to the view that's holding it's centerY (ie Center in view vertically).

I've attached an example of what the constraint look like (I've added the views above and below just to show that it can be constrained to an area based on the view that's holding it's constraints)

Your Code is here below with the minor adjustments:

#import "ViewController.h"

@interface ViewController ()
@property (strong, nullable) IBOutlet UITextView *scrollingTextView;
@end

@implementation ViewController

- (void)viewDidLoad {
    [super viewDidLoad];
    NSString *reallyLongString = @"Really Long String here";
    // your code to adjust it below
    NSMutableAttributedString * attrStr = [[NSMutableAttributedString alloc] initWithData:[reallyLongString dataUsingEncoding:NSUTF8StringEncoding] options:@{ NSDocumentTypeDocumentAttribute: NSHTMLTextDocumentType } documentAttributes:nil error:nil];

    __block BOOL found = NO;
    [attrStr beginEditing];
    [attrStr enumerateAttribute:NSFontAttributeName inRange:NSMakeRange(0, attrStr.length) options:0 usingBlock:^(id value, NSRange range, BOOL *stop) {
        if (value) {
            UIFont *oldFont = (UIFont *)value;
            UIFont *newFont = [oldFont fontWithSize:23];
            [attrStr addAttribute:NSFontAttributeName value:newFont range:range];
            [attrStr addAttribute:NSForegroundColorAttributeName
                            value:[UIColor darkGrayColor]
                            range:range];

            found = YES;
        }
    }];
    if (!found) {
        // No font was found - do something else?
    }
    [attrStr endEditing];
    [self.scrollingTextView setAttributedText:attrStr];
    // Do any additional setup after loading the view, typically from a nib.
}


@end