Ok, based on my research and other answers, the problem was the UITextView's content height and not the scrolling to a specific offset. Here is a solution that works the way it should work for iOS 7:
First, you need to recreate the UITextView like this:
NSString *reqSysVer = @"7.0";
NSString *currSysVer = [[UIDevice currentDevice] systemVersion];
BOOL osVersionSupported = ([currSysVer compare:reqSysVer options:NSNumericSearch] != NSOrderedAscending);
if (osVersionSupported) {
NSLog(@"reset chatoutput");
CGRect outputFrame = self.chatOutput.frame;
[chatOutput removeFromSuperview];
[chatOutput release];
chatOutput = nil;
NSTextStorage* textStorage = [[NSTextStorage alloc] init];
NSLayoutManager* layoutManager = [NSLayoutManager new];
[textStorage addLayoutManager:layoutManager];
NSTextContainer *textContainer = [[NSTextContainer alloc] initWithSize:self.view.bounds.size];
[layoutManager addTextContainer:textContainer];
chatOutput = [[UITextView alloc] initWithFrame: outputFrame
textContainer: textContainer];
// if using ARC, remove these 3 lines
[textContainer release];
[layoutManager release];
[textStorage release];
[self.view addSubview: chatOutput];
}
Then, use this method to get the UITextView content height:
- (CGFloat)textViewHeightForAttributedText:(NSAttributedString*)text andWidth:(CGFloat)width
{
UITextView *calculationView = [[UITextView alloc] init];
[calculationView setAttributedText:text];
CGSize size = [calculationView sizeThatFits:CGSizeMake(width, FLT_MAX)];
NSLog(@"size: %f", size.height) ;
return size.height;
}
Now you can set the content offset:
CGPoint bottomOffset;
bottomOffset = CGPointMake(0, [self textViewHeightForAttributedText: self.chatOutput.attributedText andWidth: self.chatOutput.frame.size.width] - self.chatOutput.frame.size.height);
[self.chatOutput setContentOffset:bottomOffset animated:YES];
UPDATE
I've read this in the Apple Documentation for NSAttributedString:
"The default font for NSAttributedString objects is Helvetica 12-point, which may differ from the default system font for the platform."
In conclusion, if you use different fonts of different sizes, you have to set those to the NSAttributeString instance as well. Otherwise, the returned height won't correspond to your expectations. You may want to use something like this:
NSDictionary *attrsDictionary = [NSDictionary dictionaryWithObject: [UIFont systemFontOfSize: 18.0] //or any other font or size
forKey: NSFontAttributeName];
NSAttributedString *attributedString = [[NSAttributedString alloc] initWithString: currentPost.postMessageText attributes: attrsDictionary];
frame.size.height = [self textViewHeightForAttributedText: attributedString andWidth: 280.0];
[attributedString release];
