为什么我设置UILabel的前导，顶部，尾随约束，Label约束仍然超出约束？

Question

[self addConstraint:[self.statusLabel.leadingAnchor constraintEqualToAnchor:self.avatar.leadingAnchor constant:0]];
[self addConstraint:[self.statusLabel.topAnchor constraintEqualToAnchor:self.avatar.bottomAnchor constant:10 priority:999]];
[self addConstraint:[self.statusLabel.trailingAnchor constraintEqualToAnchor:self.trailingAnchor constant:-10]];

这是视图调试器快照