我尝试更改下面的代码，注释textContainerInset和contentInset，当我添加文本时无法找出容器的框架如何变化，textView的委托中似乎也没有任何内容。
- (void)jsq_configureTextView
{
[self setTranslatesAutoresizingMaskIntoConstraints:NO];
CGFloat cornerRadius = 6.0f;
self.backgroundColor = [UIColor whiteColor];
self.layer.borderWidth = 0.5f;
self.layer.borderColor = [UIColor lightGrayColor].CGColor;
self.layer.cornerRadius = cornerRadius;
self.scrollIndicatorInsets = UIEdgeInsetsMake(cornerRadius, 0.0f, cornerRadius, 0.0f);
self.textContainerInset = UIEdgeInsetsMake(4.0f, 2.0f, 4.0f, 2.0f);
self.contentInset = UIEdgeInsetsMake(1.0f, 0.0f, 1.0f, 0.0f);
self.scrollEnabled = YES;
self.scrollsToTop = NO;
self.userInteractionEnabled = YES;
self.font = [UIFont systemFontOfSize:16.0f];
self.textColor = [UIColor blackColor];
self.textAlignment = NSTextAlignmentNatural;
self.contentMode = UIViewContentModeRedraw;
self.dataDetectorTypes = UIDataDetectorTypeNone;
self.keyboardAppearance = UIKeyboardAppearanceDefault;
self.keyboardType = UIKeyboardTypeDefault;
self.returnKeyType = UIReturnKeyDefault;
self.text = nil;
_placeHolder = nil;
_placeHolderTextColor = [UIColor lightGrayColor];
[self jsq_addTextViewNotificationObservers];
}