場景：autoLayout自動佈局 ，在UITableView的cell中新增UILabel，UILabel需要多行顯示。

我原先的設定的約束：

//新增子控制元件
- (void)addComponents
{
    self.tagView = [[UIView alloc] init];
    [self addSubview:self.tagView];
    
    self.descLabel = [[UILabel alloc] init];
    self.descLabel.numberOfLines = 0;
    self.descLabel.lineBreakMode = NSLineBreakByWordWrapping;//拆行
    [self addSubview:self.descLabel];
}
 

//新增約束
- (void)addContraints
{
    [self.tagView tn_pinEdgeToSuperviewEdge:TNAEdgeLeading withInset:10.0f];
    [self.tagView tn_pinEdgeToSuperviewEdge:TNAEdgeTop withInset:2.0f];
    [self.tagView tn_setDimension:TNADimensionWidth toSize:50.0f];
    [self.tagView tn_setDimension:TNADimensionHeight toSize:21.0f];
    
    [self.descLabel tn_pinEdge:TNAEdgeLeading toEdge:TNAEdgeTrailing ofView:self.tagView withOffset:0.0f];
    [self.descLabel tn_pinEdgeToSuperviewEdge:TNAEdgeTop withInset:2.0f];
}
 

最後解決如下，在約束中再新增一個約束，讓UILabel依靠父view的右邊

[self.descLabel tn_pinEdgeToSuperviewEdge:TNAEdgeTrailing withInset:0.0f];