简单写了下 iOS GPT 应用流式输出 + 可追随光标 也没什么代码，就直接传了。
对于我想要实现的方案来说，整体就是一个textView，关于光标或者头像位置，则采用计算方式放置。
关于分行头像展示问题，我的方案是：
- 使用textview同等字体、间距文本属性，计算文本高度，放置图像在左侧即可。插入到TextView持有的滚动视图指定位置。
关于光标追随，我的方案是：
- 如下代码
- (void)viewDidLoad {
[super viewDidLoad];
NSString *filePath = [[NSBundle mainBundle] pathForResource:@"news" ofType:@"txt"];
NSError *error = nil;
NSString *fileContents = [NSString stringWithContentsOfFile:filePath encoding:NSUTF8StringEncoding error:&error];
if (error) {
NSLog(@"Error reading file: %@", error.localizedDescription);
} else {
self.curNews = fileContents;
}
self.textView = [[UITextView alloc] init];
self.textView.font = [UIFont systemFontOfSize:16];
self.textView.backgroundColor = [UIColor whiteColor];
self.textView.editable = NO;
self.textView.textContainerInset = UIEdgeInsetsMake(64, 20, 0, 20);
self.textView.translatesAutoresizingMaskIntoConstraints = NO;
[self.view addSubview:self.textView];
[NSLayoutConstraint activateConstraints:@[
[self.textView.topAnchor constraintEqualToAnchor:self.view.topAnchor constant:0],
[self.textView.leadingAnchor constraintEqualToAnchor:self.view.leadingAnchor constant:0],
[self.textView.bottomAnchor constraintEqualToAnchor:self.view.bottomAnchor constant:-33],
[self.textView.trailingAnchor constraintEqualToAnchor:self.view.trailingAnchor constant:0]
]];
self.cursorView = [[UIImageView alloc] initWithFrame:CGRectZero];
self.cursorView.backgroundColor = [UIColor blueColor];
self.cursorView.layer.masksToBounds = YES;
self.cursorView.layer.cornerRadius = 15/2.0;
[self.view addSubview:self.cursorView];
// 每隔0.5秒钟，将内容输出到textView
[NSTimer scheduledTimerWithTimeInterval:0.5 target:self selector:@selector(addText) userInfo:nil repeats:YES];
}
- (void)addText {
if (cur < [self.curNews length]) {
float t = (arc4random() % 3 + 1) / 10.0;
[NSThread sleepForTimeInterval:t];
int read = arc4random() % 15;
if ((cur + read) > self.curNews.length) {
read = (int)self.curNews.length - cur;
}
[self.textView insertText:[self.curNews substringWithRange:NSMakeRange(cur, read)]];
UITextRange *selectedRange = self.textView.selectedTextRange;
CGRect cursorRect = [self.textView caretRectForPosition:selectedRange.start];
cursorRect = CGRectInset(cursorRect, 0, 3);
cursorRect.size = CGSizeMake(15, 15);
if (cursorRect.origin.y > CGRectGetMaxY(self.textView.frame)) {
[self.textView setContentOffset:CGPointMake(0, self.textView.contentSize.height - self.textView.frame.size.height) animated:NO];
cursorRect.origin.y = CGRectGetMaxY(self.textView.frame) - 15 - 2;
}
[UIView animateWithDuration:0.1 animations:^{
self.cursorView.alpha = 0.3;
self.cursorView.frame = CGRectOffset(cursorRect, self.textView.frame.origin.x, self.textView.frame.origin.y);
} completion:^(BOOL finished) {
[UIView animateWithDuration:0.05 animations:^{
self.cursorView.alpha = 0.8;
}];
}];
cur += read;
} else {
cur = 0;
self.textView.text = @""; // 清空
}
}
@end