如何从界面生成器设置uitextview的垂直对齐方式

Question

我的应用程序设计有问题.我想在我的UITextView中间设置垂直对齐.请帮我如何从界面构建器设置uitextview的垂直对齐.

Answer 1

通过观察对contentSize属性的更改然后设置contentOffset来实现此目的.

- (void)viewDidLoad{
    [super viewDidLoad];
    [myTextView addObserver:self forKeyPath:@"contentSize" options:(NSKeyValueObservingOptionNew) context:nil];
}

-(void)observeValueForKeyPath:(NSString *)keyPath ofObject:(id)object change:(NSDictionary *)change context:(void *)context {
    UITextView *myView = object;

    CGFloat offSet = ([myView bounds].size.height - [myView contentSize].height * [myView zoomScale])/2.0;
    offSet = offSet < 0.0 ? 0.0 : offSet;
    [myView setContentOffset:CGPointMake(0, -offSet) animated:NO]; 
}