介绍地址：http://www.cocoachina.com/ios/20141219/10702.html
官网：https://github.com/SnapKit/Masonry
记住：一定要先添加View , 再设置位置
NSLayout 相关枚举
typedef NS_ENUM(NSInteger, NSLayoutRelation) {
NSLayoutRelationLessThanOrEqual = -1, //小于等于
NSLayoutRelationEqual = 0, //等于
NSLayoutRelationGreaterThanOrEqual = 1, //大于等于
};
typedef NS_ENUM(NSInteger, NSLayoutAttribute) {
NSLayoutAttributeLeft = 1, //左侧
NSLayoutAttributeRight, //右侧
NSLayoutAttributeTop, //上方
NSLayoutAttributeBottom, //下方
NSLayoutAttributeLeading, //首部
NSLayoutAttributeTrailing, //尾部
NSLayoutAttributeWidth, //宽度
NSLayoutAttributeHeight, //高度
NSLayoutAttributeCenterX, //X轴中心
NSLayoutAttributeCenterY, //Y轴中心
NSLayoutAttributeBaseline, //文本底标线
NSLayoutAttributeNotAnAttribute = 0 //没有属性
};
左右顶部宽高一样：
make.left.right.and.top.equalTo(self);
实际使用
/** * 底部购买栏 初始化 */ - (void)setupFooterView { CGFloat footerViewH = 50; // 背景栏 UIView *footerView = [[UIView alloc] init]; footerView.backgroundColor = [UIColor whiteColor]; footerView.layer.borderColor = [UIColor colorWithHexString:Color_Line].CGColor; footerView.layer.borderWidth = 0.3; [self.view addSubview:footerView]; // 首页 UIButton *homeBtn = [UIButton buttonWithType:UIButtonTypeCustom]; homeBtn.titleLabel.font = [UIFont systemFontOfSize:12]; homeBtn.layer.borderWidth = 0.3; homeBtn.layer.borderColor = [UIColor colorWithHexString:Color_Line].CGColor; [homeBtn setTitle:@"首页" forState:UIControlStateNormal]; [homeBtn setTitleColor:[UIColor colorWithHexString:@"6c6c6c"] forState:UIControlStateNormal]; [homeBtn setImage:[UIImage imageNamed:@"home"] forState:UIControlStateNormal]; [homeBtn setImageEdgeInsets:UIEdgeInsetsMake(-14, 12.5, 0, 0)]; [homeBtn setTitleEdgeInsets:UIEdgeInsetsMake(18, -22, 0, 0)]; [homeBtn addTarget:self action:@selector(homeClick) forControlEvents:UIControlEventTouchUpInside]; [footerView addSubview:homeBtn]; // 加入购物车 UIButton *addCartBtn = [UIButton buttonWithType:UIButtonTypeCustom]; addCartBtn.backgroundColor = [UIColor colorWithHexString:@"fc714b"]; addCartBtn.titleLabel.font = [UIFont systemFontOfSize:16]; [addCartBtn setTitle:@"加入购物车" forState:UIControlStateNormal]; [addCartBtn setTitleColor:[UIColor colorWithHexString:@"ffffff"] forState:UIControlStateNormal]; [addCartBtn setBackgroundImage:[Tool createImageWithColor:[UIColor colorWithHexString:Color_Line]] forState:UIControlStateSelected]; [addCartBtn addTarget:self action:@selector(buyClick:) forControlEvents:UIControlEventTouchUpInside]; [footerView addSubview:addCartBtn]; if (![self.goodsDetail.goods.only_one_step_buy isEqualToString:@"0"]) { addCartBtn.selected = YES; addCartBtn.userInteractionEnabled = NO; } // 立即购买 UIButton *buyBtn = [UIButton buttonWithType:UIButtonTypeCustom]; buyBtn.backgroundColor = [UIColor colorWithHexString:Color_Red]; buyBtn.titleLabel.font = [UIFont systemFontOfSize:16]; [buyBtn setTitle:@"立即购买" forState:UIControlStateNormal]; [buyBtn setTitleColor:[UIColor colorWithHexString:@"ffffff"] forState:UIControlStateNormal]; [buyBtn setBackgroundImage:[Tool createImageWithColor:[UIColor colorWithHexString:@"e8e8e8"]] forState:UIControlStateSelected]; [buyBtn addTarget:self action:@selector(buyClick:) forControlEvents:UIControlEventTouchUpInside]; [footerView addSubview:buyBtn]; // 库存为0，底部按钮变灰 if ([self.goodsDetail.goods.goods_number intValue] <= 0) { buyBtn.selected = YES; buyBtn.userInteractionEnabled = NO; addCartBtn.selected = YES; addCartBtn.userInteractionEnabled = NO; } [footerView mas_makeConstraints:^(MASConstraintMaker *make) { make.size.mas_equalTo(CGSizeMake(ScreenWidth,footerViewH)); make.bottom.mas_equalTo(@0); }]; [homeBtn mas_makeConstraints:^(MASConstraintMaker *make) { make.top.equalTo(footerView.mas_top); make.left.equalTo(footerView.mas_left); make.bottom.equalTo(footerView.mas_bottom); make.width.equalTo(@54); make.height.equalTo(footerView.mas_height); }]; [addCartBtn mas_makeConstraints:^(MASConstraintMaker *make) { make.top.equalTo(footerView.mas_top); make.left.equalTo(homeBtn.mas_right); make.bottom.equalTo(footerView.mas_bottom); make.right.equalTo(buyBtn.mas_left); make.width.equalTo(@[addCartBtn,buyBtn]); make.height.equalTo(footerView.mas_height); }]; [buyBtn mas_makeConstraints:^(MASConstraintMaker *make) { make.top.equalTo(footerView.mas_top); make.left.equalTo(addCartBtn.mas_right); make.bottom.equalTo(footerView.mas_bottom); make.right.equalTo(footerView.mas_right); make.width.equalTo(@[addCartBtn,buyBtn]); make.height.equalTo(footerView.mas_height); }]; _footerView = footerView; }
效果：
两个元素相对居中
效果红色框如：
具体代码：
UIView *couponView = [[UIView alloc] init]; couponView.backgroundColor = [UIColor redColor]; [payInfoView addSubview:couponView]; //父控件 加入 容器 [couponView mas_makeConstraints:^(MASConstraintMaker *make) { //make.height.top.centerX.equalTo(couponView.superview);//width不设置，让其根据子控件宽度进行适配 make.centerX.equalTo(payInfoView); make.height.mas_equalTo(payInfoViewFooterH); make.bottom.mas_equalTo(payInfoView.mas_bottom); }]; // 已优惠 UILabel *couponLabel = [[UILabel alloc] init]; couponLabel.textColor = VSColorFromRGB(0x585c64); couponLabel.font = [UIFont systemFontOfSize:12]; [couponView addSubview:couponLabel]; couponLabel.text = [NSString stringWithFormat:@"已优惠￥%@",@"123"]; // 点击详情 UIButton *couponLookDescButton = [UIButton buttonWithType:UIButtonTypeCustom]; [couponLookDescButton setImage:[UIImage imageNamed:@"pay_instalment_explain"] forState:UIControlStateNormal]; [couponView addSubview:couponLookDescButton]; [couponLabel mas_makeConstraints:^(MASConstraintMaker *make) { make.left.equalTo(couponView); make.centerY.equalTo(couponView); make.right.equalTo(couponLookDescButton.mas_left).offset(-5); }]; [couponLookDescButton mas_makeConstraints:^(MASConstraintMaker *make) { make.left.equalTo(couponLabel.mas_right).offset(5); make.centerY.equalTo(couponView); make.right.equalTo(couponView); }];
计算自动约束高度
// 最终总高度 [_payPeriodBgImageView mas_makeConstraints:^(MASConstraintMaker *make) { make.top.equalTo(self); make.left.right.equalTo(self); make.bottom.equalTo(_periodDetailListView.mas_bottom); }]; // 更新约束 [self layoutIfNeeded]; // 视图的最大 Y 值 CGFloat h= CGRectGetMaxY(_payPeriodBgImageView.frame);
mas_makeConstraints && mas_remakeConstraints && mas_updateConstraints 用法与注意事项
1 mas_makeConstraints 只负责新增约束,Autolayout 不能同时存在两条针对于同一对象约束 否则会报错
注意:在添加约束之前一定要添加到view( [testView addSubview:self.view])上 否则会报错
[testView mas_makeConstraints:^(MASConstraintMaker *make) {
make.leading.equalTo(view1.mas_trailing).offset(10);
make.bottom.equalTo(view2.mas_bottom).offset(-2);
make.height.mas_equalTo(70);
make.width.mas_equalTo(50);
}];
2 mas_remakeConstraints 会清除之前的所有约束 仅保留最新的约束
如下:会清除原来的以view1 和view2 为参照的约束 保留 以view3 和view4 为参照的约束
[testView mas_remakeConstraints :^(MASConstraintMaker *make) {
make.bottom.equalTo(view3.mas_top).offset(-10);
make.centerX.equalTo(view4.mas_centerX);
make.height.mas_equalTo(70);
make.width.mas_equalTo(50);
}];
3 mas_updateConstraints 针对上面的情况 会更新block中出现的约束 不会导致出现两个相同的约束的情况
注意: 同一个对象 使用mas_updateConstraints 一定要保证 block中要更新的元素是 其使用mas_makeConstraints 设置的约束
如下就是正确的 则不会出现约束冲突问题
[testView mas_updateConstraints:^(MASConstraintMaker *make) {
make.bottom.equalTo(view1.mas_top).offset(-60);
必须是 同一参照对象(都是以view1)同一参照属性(都是以view1的mas_top)
}];
但是下面的就不对了 就会出现约束冲突 在iOS 7 及其以下会出现由于约束冲突出现的崩溃
[testView mas_updateConstraints:^(MASConstraintMaker *make) {
make.bottom.equalTo(view2.mas_top).offset(-10);
make.centerX.equalTo(view4.mas_centerX);
原因1:不同一参照对象 (原来是view1 现在是view2)
原因2 testView 在 mas_makeConstraints中没有设置 center 所以无法更新
}];
解决办法:使用mas_remakeConstraints 清除原来的约束 重新设置约束;
}];
其它可参考：http://www.jianshu.com/p/2b57ece2b3b8