I've found code from answers on previous questions that calculate the range of the visible attributed text in a UITextView. It works perfectly, except after I add in newline characters of any type in order to create a new paragraph. In this case, the code gives the incorrect answer, until I manually scroll the view. After scrolling, it gives the correct answer every time. But I need it to give the right answer even without scrolling.
Below is my sample project. It is a single view application. The program reports in the logging what text it believes to be visible, the first time after the view loads, and then after scrolling.
ViewController.h
#import <UIKit/UIKit.h>
@interface ViewController : UIViewController <UIScrollViewDelegate> {
UITextView *lTextView;
}
@end
ViewController.m
#import "ViewController.h"
@interface ViewController ()
@end
@implementation ViewController
- (void)viewDidLoad {
[super viewDidLoad];
int statusBarHeight = 20;
UIScrollView *scrollView;
scrollView = [[UIScrollView alloc] initWithFrame:CGRectMake(0, statusBarHeight, self.view.frame.size.width * 2, self.view.frame.size.height)];
scrollView.pagingEnabled = YES;
scrollView.delegate = self;
[self.view addSubview:scrollView];
lTextView = [[UITextView alloc] initWithFrame:CGRectMake(0, 0, scrollView.frame.size.width/2, scrollView.frame.size.height)];
lTextView.editable = NO;
lTextView.selectable = NO;
lTextView.attributedText = [self loremIpsum];
[scrollView addSubview:lTextView];
lTextView.delegate = self;
[self report];
}
- (void)report {
NSArray *visibleRange = [self visibleRangeOfTextView:lTextView];
NSNumber *start = [visibleRange objectAtIndex:0];
NSNumber *end = [visibleRange objectAtIndex:1];
int rangeLength = (end.intValue - start.intValue);
NSLog(@"%@", [lTextView.text substringWithRange:NSMakeRange(start.intValue, rangeLength)]);
}
-(NSArray *)visibleRangeOfTextView:(UITextView *)textView {
CGRect bounds = textView.bounds;
bounds.size.height -= 30.0; // to prevent including lines that can barely be seen at the bottom
UITextPosition *start = [textView characterRangeAtPoint:bounds.origin].start;
UITextPosition *end = [textView characterRangeAtPoint:CGPointMake(CGRectGetMaxX(bounds), CGRectGetMaxY(bounds))].end; // <<<< this gives an incorrect calculation until the user manually scrolls
float startOffset = [textView offsetFromPosition:textView.beginningOfDocument toPosition:start];
float endOffset = [textView offsetFromPosition:textView.beginningOfDocument toPosition:end];
NSLog(@"startOffset: %f, endOffset %f", startOffset, endOffset);
return [NSArray arrayWithObjects:[NSNumber numberWithFloat:startOffset], [NSNumber numberWithFloat:endOffset], nil];
}
- (void)scrollViewDidEndDecelerating:(UIScrollView *)scrollView {
NSLog(@"scrollViewDidEndDecelerating");
[self report];
}
- (void)scrollViewDidEndDragging:(UIScrollView *)scrollView willDecelerate:(BOOL)decelerate {
NSLog(@"scrollViewDidEndDragging");
[self report];
}
- (NSAttributedString *)loremIpsum {
NSMutableAttributedString *li = [[NSMutableAttributedString alloc] init];
NSArray *strings = [NSArray arrayWithObjects:@"1 Lorem ipsum dolor sit amet, consectetur adipiscing elit. Aliquam congue eleifend risus eget pretium. Donec sed commodo neque, id ornare dolor.", @" 2 Vivamus vestibulum non quam et euismod. Morbi et dolor luctus velit lobortis ornare vel vel tellus. Vestibulum ante ipsum primis in faucibus orci luctus et ultrices posuere cubilia Curae; Aenean viverra, urna nec tempor commodo, turpis nisl rhoncus mauris, in ullamcorper justo sapien quis nulla.", @" 3 Aliquam at odio molestie, laoreet elit sed, suscipit risus. Nulla eleifend, quam eget porttitor condimentum, metus lacus lobortis ligula, accumsan tristique neque turpis non purus. Aenean malesuada tortor id elit semper, et pretium nulla viverra.", @" 4 Aliquam sollicitudin placerat massa, quis posuere est ornare vel. Nam mollis convallis risus a tincidunt. Class aptent taciti sociosqu ad litora torquent per conubia nostra, per inceptos himenaeos.", @" 5 Fusce facilisis orci nisi, vel egestas metus tristique vitae. Proin nec malesuada dolor. Donec eget felis accumsan, facilisis turpis vitae, blandit lacus.", @" 6 Pellentesque auctor nisl quis turpis commodo lacinia. In sed euismod urna. Praesent sed commodo magna.", @" 7 Ut interdum dignissim urna, nec feugiat dolor. Nulla facilisi. Donec fermentum mauris at ante tincidunt, id accumsan eros lacinia.", @" 8 Suspendisse potenti. Integer ac mattis eros, sed volutpat dui. Pellentesque vehicula turpis ut metus malesuada blandit.", @" 9 Nam laoreet dui id imperdiet pulvinar. In auctor enim ac massa feugiat adipiscing. Nam convallis neque at felis tincidunt iaculis. Maecenas dictum est ac nulla suscipit, nec condimentum metus molestie.", @" 10 Vestibulum mollis velit eu nunc eleifend egestas. Ut aliquam ultrices tellus volutpat consectetur. Morbi eget sollicitudin quam, ut imperdiet leo. Morbi sed ligula iaculis, tincidunt diam nec, pharetra ligula.", @" 11 Class aptent taciti sociosqu ad litora torquent per conubia nostra, per inceptos himenaeos. Proin varius facilisis placerat. Fusce suscipit risus risus, in varius diam convallis quis. In hac habitasse platea dictumst. Integer non lectus non dolor fringilla venenatis eget quis nisl. Proin in pretium metus.", @" 12 Pellentesque sed tellus iaculis, bibendum neque vel, porta ante. Phasellus eu vulputate massa. Nullam venenatis lectus non nunc aliquet porta. Nunc gravida rutrum feugiat. Fusce elit nunc, facilisis non tristique placerat, tempor id orci. Mauris et massa cursus, dapibus urna a, condimentum arcu. Pellentesque vitae sagittis sapien. Ut lacus purus, suscipit at magna non, rhoncus luctus dui. Ut ipsum augue, pharetra ac ipsum sed, facilisis convallis justo.", @" 13 Ut arcu augue, hendrerit vel tincidunt vitae, aliquet ac quam. Nulla ullamcorper, dolor eu pellentesque cursus, lectus quam interdum ante, nec congue dui augue nec dolor. Sed convallis elit in enim dictum, at posuere sem mollis. Praesent in metus aliquam, ullamcorper purus tempor, mattis ipsum. Aliquam gravida, sem vitae iaculis placerat, dui velit commodo nulla, vitae ultrices lectus dolor ut mi.", @" 14 Suspendisse quis metus varius, congue turpis vitae, viverra nunc. Duis placerat, felis et laoreet pretium, nibh lorem pulvinar turpis, eu euismod arcu libero at mauris. Sed laoreet, eros in tempor accumsan, odio augue fermentum dui, a pharetra felis libero eu ligula.", @"Suspendisse ultricies pulvinar urna. Donec placerat nulla non elit vestibulum mattis.", @"Phasellus semper sem a sem dignissim tempus. Sed scelerisque sed purus interdum rhoncus. Sed gravida eros sit amet dui fermentum rutrum. Proin a arcu scelerisque, volutpat orci quis, dignissim neque. Aliquam erat volutpat. Sed eget scelerisque neque.", nil];
for (int i = 0; i < strings.count; i++) {
NSString *string = [strings objectAtIndex:i];
if (i != 0) {
// Comment this line and it will work perfectly:
[li appendAttributedString:[[NSAttributedString alloc] initWithString:@"\n\n"]];
}
[li appendAttributedString:[[NSAttributedString alloc] initWithString:string]];
}
return li;
}
@end
Thanks for any assistance!
I came up with a solution on the day that I added the bounty, but did not post it so that others would have a chance to post something helpful to others. Mr. Bajorek and rintaro both posted answers that worked. My solution was a bit different; it better suits what I am trying to do in my project (since I will use multiple UITextViews). It disables scrolling in the UITextView, lets the UIScrollView handle the scrolling, and adds the UITextView with the full height needed to accommodate all of the attributed text. This allowed the calculation to work correctly from the beginning.
For the benefit of others who might read later, I post a complete working example below. I will mark this as the accepted answer since this is the route I went before the other solutions were posted.
ViewController.h
#import <UIKit/UIKit.h>
@interface ViewController : UIViewController <UIScrollViewDelegate> {
UITextView *lTextView;
UIScrollView *scrollView;
}
@end
ViewController.m
#import "ViewController.h"
@interface ViewController ()
@end
@implementation ViewController
- (void)viewDidLoad {
[super viewDidLoad];
int statusBarHeight = 20;
scrollView = [[UIScrollView alloc] initWithFrame:CGRectMake(0, statusBarHeight, self.view.frame.size.width, self.view.frame.size.height)];
[self.view addSubview:scrollView];
lTextView = [[UITextView alloc] init];
lTextView.editable = NO;
lTextView.selectable = NO;
lTextView.scrollEnabled = NO;
lTextView.textContainerInset = UIEdgeInsetsZero;
lTextView.attributedText = [self loremIpsum];
float calculatedHeight = [self heightForTextViewWithAttributedText:lTextView andWidth:scrollView.frame.size.width];
lTextView.frame = CGRectMake(0, 0, scrollView.frame.size.width, calculatedHeight);
[scrollView addSubview:lTextView];
[scrollView setContentSize:CGSizeMake(scrollView.frame.size.width, calculatedHeight + 20)];
scrollView.delegate = self;
[self report];
}
- (void)report {
NSArray *visibleRange = [self visibleRangeOfTextView:lTextView];
NSNumber *start = [visibleRange objectAtIndex:0];
NSNumber *end = [visibleRange objectAtIndex:1];
int rangeLength = (end.intValue - start.intValue);
NSLog(@"%@", [lTextView.text substringWithRange:NSMakeRange(start.intValue, rangeLength)]);
}
-(NSArray *)visibleRangeOfTextView:(UITextView *)textView {
double offsetY = scrollView.contentOffset.y;
CGPoint startingPoint = scrollView.contentOffset;
startingPoint.y += 5; // to prevent including lines that can barely be seen at the top
CGPoint endingPoint = CGPointMake(320, offsetY + scrollView.frame.size.height - 20);
CGRect bounds = textView.bounds;
bounds.size.height -= 30.0; // to prevent including lines that can barely be seen at the bottom
UITextPosition *start = [textView characterRangeAtPoint:startingPoint].start;
UITextPosition *end = [textView characterRangeAtPoint:endingPoint].end;
float startOffset = [textView offsetFromPosition:textView.beginningOfDocument toPosition:start];
float endOffset = [textView offsetFromPosition:textView.beginningOfDocument toPosition:end];
return [NSArray arrayWithObjects:[NSNumber numberWithFloat:startOffset], [NSNumber numberWithFloat:endOffset], nil];
}
- (void)scrollViewDidEndDecelerating:(UIScrollView *)scrollView {
NSLog(@"scrollViewDidEndDecelerating");
[self report];
}
- (void)scrollViewDidEndDragging:(UIScrollView *)scrollView willDecelerate:(BOOL)decelerate {
NSLog(@"scrollViewDidEndDragging");
[self report];
}
- (NSAttributedString *)loremIpsum {
NSMutableAttributedString *li = [[NSMutableAttributedString alloc] init];
NSArray *strings = [NSArray arrayWithObjects:@"1 Lorem ipsum dolor sit amet, consectetur adipiscing elit. Aliquam congue eleifend risus eget pretium. Donec sed commodo neque, id ornare dolor.", @" 2 Vivamus vestibulum non quam et euismod. Morbi et dolor luctus velit lobortis ornare vel vel tellus. Vestibulum ante ipsum primis in faucibus orci luctus et ultrices posuere cubilia Curae; Aenean viverra, urna nec tempor commodo, turpis nisl rhoncus mauris, in ullamcorper justo sapien quis nulla.", @" 3 Aliquam at odio molestie, laoreet elit sed, suscipit risus. Nulla eleifend, quam eget porttitor condimentum, metus lacus lobortis ligula, accumsan tristique neque turpis non purus. Aenean malesuada tortor id elit semper, et pretium nulla viverra.", @" 4 Aliquam sollicitudin placerat massa, quis posuere est ornare vel. Nam mollis convallis risus a tincidunt. Class aptent taciti sociosqu ad litora torquent per conubia nostra, per inceptos himenaeos.", @" 5 Fusce facilisis orci nisi, vel egestas metus tristique vitae. Proin nec malesuada dolor. Donec eget felis accumsan, facilisis turpis vitae, blandit lacus.", @" 6 Pellentesque auctor nisl quis turpis commodo lacinia. In sed euismod urna. Praesent sed commodo magna.", @" 7 Ut interdum dignissim urna, nec feugiat dolor. Nulla facilisi. Donec fermentum mauris at ante tincidunt, id accumsan eros lacinia.", @" 8 Suspendisse potenti. Integer ac mattis eros, sed volutpat dui. Pellentesque vehicula turpis ut metus malesuada blandit.", @" 9 Nam laoreet dui id imperdiet pulvinar. In auctor enim ac massa feugiat adipiscing. Nam convallis neque at felis tincidunt iaculis. Maecenas dictum est ac nulla suscipit, nec condimentum metus molestie.", @" 10 Vestibulum mollis velit eu nunc eleifend egestas. Ut aliquam ultrices tellus volutpat consectetur. Morbi eget sollicitudin quam, ut imperdiet leo. Morbi sed ligula iaculis, tincidunt diam nec, pharetra ligula.", @" 11 Class aptent taciti sociosqu ad litora torquent per conubia nostra, per inceptos himenaeos. Proin varius facilisis placerat. Fusce suscipit risus risus, in varius diam convallis quis. In hac habitasse platea dictumst. Integer non lectus non dolor fringilla venenatis eget quis nisl. Proin in pretium metus.", @" 12 Pellentesque sed tellus iaculis, bibendum neque vel, porta ante. Phasellus eu vulputate massa. Nullam venenatis lectus non nunc aliquet porta. Nunc gravida rutrum feugiat. Fusce elit nunc, facilisis non tristique placerat, tempor id orci. Mauris et massa cursus, dapibus urna a, condimentum arcu. Pellentesque vitae sagittis sapien. Ut lacus purus, suscipit at magna non, rhoncus luctus dui. Ut ipsum augue, pharetra ac ipsum sed, facilisis convallis justo.", @" 13 Ut arcu augue, hendrerit vel tincidunt vitae, aliquet ac quam. Nulla ullamcorper, dolor eu pellentesque cursus, lectus quam interdum ante, nec congue dui augue nec dolor. Sed convallis elit in enim dictum, at posuere sem mollis. Praesent in metus aliquam, ullamcorper purus tempor, mattis ipsum. Aliquam gravida, sem vitae iaculis placerat, dui velit commodo nulla, vitae ultrices lectus dolor ut mi.", @" 14 Suspendisse quis metus varius, congue turpis vitae, viverra nunc. Duis placerat, felis et laoreet pretium, nibh lorem pulvinar turpis, eu euismod arcu libero at mauris. Sed laoreet, eros in tempor accumsan, odio augue fermentum dui, a pharetra felis libero eu ligula.", @"Suspendisse ultricies pulvinar urna. Donec placerat nulla non elit vestibulum mattis.", @"Phasellus semper sem a sem dignissim tempus. Sed scelerisque sed purus interdum rhoncus. Sed gravida eros sit amet dui fermentum rutrum. Proin a arcu scelerisque, volutpat orci quis, dignissim neque. Aliquam erat volutpat. Sed eget scelerisque neque.", nil];
for (int i = 0; i < strings.count; i++) {
NSString *string = [strings objectAtIndex:i];
if (i != 0) {
// Comment this line and it will work perfectly:
[li appendAttributedString:[[NSAttributedString alloc] initWithString:@"\n\n"]];
}
[li appendAttributedString:[[NSAttributedString alloc] initWithString:string]];
}
return li;
}
- (CGFloat)heightForTextViewWithAttributedText:(UITextView *)textView andWidth:(CGFloat)width
{
CGSize size = [textView sizeThatFits:CGSizeMake(width, FLT_MAX)];
return size.height + 3.0;
}
@end