堆棧視圖使用內(nèi)部?jī)?nèi)容大小，因此使用布局約束來(lái)定義視圖的尺寸。
有一種簡(jiǎn)單的方法可以快速添加約束（示例）：
[view1.heightAnchor constraintEqualToConstant:100].active = true;
完整的代碼：
- (void) setup {
//View 1
UIView *view1 = [[UIView alloc] init];
view1.backgroundColor = [UIColor blueColor];
[view1.heightAnchor constraintEqualToConstant:100].active = true;
[view1.widthAnchor constraintEqualToConstant:120].active = true;
//View 2
UIView *view2 = [[UIView alloc] init];
view2.backgroundColor = [UIColor greenColor];
[view2.heightAnchor constraintEqualToConstant:100].active = true;
[view2.widthAnchor constraintEqualToConstant:70].active = true;
//View 3
UIView *view3 = [[UIView alloc] init];
view3.backgroundColor = [UIColor magentaColor];
[view3.heightAnchor constraintEqualToConstant:100].active = true;
[view3.widthAnchor constraintEqualToConstant:180].active = true;
//Stack View
UIStackView *stackView = [[UIStackView alloc] init];
stackView.axis = UILayoutConstraintAxisVertical;
stackView.distribution = UIStackViewDistributionEqualSpacing;
stackView.alignment = UIStackViewAlignmentCenter;
stackView.spacing = 30;
[stackView addArrangedSubview:view1];
[stackView addArrangedSubview:view2];
[stackView addArrangedSubview:view3];
stackView.translatesAutoresizingMaskIntoConstraints = false;
[self.view addSubview:stackView];
//Layout for Stack View
[stackView.centerXAnchor constraintEqualToAnchor:self.view.centerXAnchor].active = true;
[stackView.centerYAnchor constraintEqualToAnchor:self.view.centerYAnchor].active = true;
}
注意：這已在iOS 9上進(jìn)行了測(cè)試
