前言
其实早在@sunnyxx同学发布 UIView-FDCollapsibleConstraints 的时候 我就说要写一下怎么用代码来稍微麻烦的实现复用的问题 但是一直各种没时间(主要是我的办法太复杂 - -) 正好看到@叶孤城同学也说了一下 他的解决办法 所以我来说一下我是如何解决这个问题的
分析
我们以叶孤城同学的例子来简单分析一下 假设view是这样的(为了方便 将所有的间隙设定为20)
正常的布局是这样的
布局代码如下:
@interface ComplexCell()
@property (nonatomic, strong) UIView *vB; //view blue height:30
@property (nonatomic, strong) UIView *vY; //view yellow height:30
@property (nonatomic, strong) UIView *vR; //view red height:30
@property (nonatomic, strong) UIView *vG; //view green height:100
@end
- (instancetype)initWithStyle:(UITableViewCellStyle)style reuseIdentifier:(NSString *)reuseIdentifier {
self = [super initWithStyle:style reuseIdentifier:reuseIdentifier];
if ( self ) {
CGFloat spacing = 20.0f;
self.vB = [UIView new];
[self.contentView addSubview:self.vB];
[self.vB mas_makeConstraints:^(MASConstraintMaker *make) {
make.left.top.equalTo(self.contentView).insets(UIEdgeInsetsMake(spacing,spacing,0,0));
make.width.equalTo(@60);
make.height.equalTo(@30).priorityLow();
self.cB = make.height.equalTo(@0).priority(UILayoutPriorityRequired);
}];
self.vB.backgroundColor = [UIColor blueColor];
self.vY = [UIView new];
[self.contentView addSubview:self.vY];
[self.vY mas_makeConstraints:^(MASConstraintMaker *make) {
make.left.equalTo(self.vB.mas_right).offset(spacing);
make.right.top.equalTo(self.contentView).insets(UIEdgeInsetsMake(spacing,0,0,spacing));
make.height.equalTo(@30).priorityLow();
self.cY = make.height.equalTo(@0).priority(UILayoutPriorityRequired);
}];
self.vY.backgroundColor = [UIColor yellowColor];
self.vR = [UIView new];
[self.contentView addSubview:self.vR];
[self.vR mas_makeConstraints:^(MASConstraintMaker *make) {
make.top.equalTo(self.vB.mas_bottom).offset(spacing);
make.left.right.equalTo(self.contentView).insets(UIEdgeInsetsMake(0,spacing,0,spacing));
make.height.equalTo(@30).priorityLow();
self.cR = make.height.equalTo(@0).priority(UILayoutPriorityRequired);
}];
self.vR.backgroundColor = [UIColor redColor];
self.vG = [UIView new];
[self.contentView addSubview:self.vG];
[self.vG mas_makeConstraints:^(MASConstraintMaker *make) {
make.top.equalTo(self.vR.mas_bottom).offset(spacing);
make.left.right.equalTo(self.contentView).insets(UIEdgeInsetsMake(0,spacing,0,spacing));
make.height.equalTo(@100).priorityLow();
self.cG = make.height.equalTo(@0).priority(UILayoutPriorityRequired);
}];
self.vG.backgroundColor = [UIColor greenColor];
[self.cB deactivate];
[self.cY deactivate];
[self.cR deactivate];
[self.cG deactivate];
}
return self;
}
}
return self;
}
实际效果如图
看上去还不错
在Masonry中 针对单条的 MASLayoutConstraint 可以进行 active 和 deactive 操作 那么意味着可以动态的启用或者禁用某条预置的约束 所以我们只要预先设置一条高优先级的高度为0(或者宽度为0)的约束 然后在适当的时候激活它不就行了? 先尝试隐藏红色的view 隐藏后如下
啊~哦~ 结果不正确 隐藏是隐藏了 但是间隙没有隐藏 导致缝变大了 这是因为我们仅仅隐藏了view 而没有隐藏view之间的间隔 那么应该如何处理这种情况呢?主流的做法是将这个view的所有约束值全设置成0 然后恢复的时候再还原 这种方法需要记录原值 但是在前言我说了 要用稍微麻烦的方法来解决这个问题 所以肯定不是这样做啦
我采用的方法是group法 具体如下图
其实在第一行还有一个groupview如图
但是因为图显示出来不太好看(不会画图 T_T ) 所以我隐藏了 具体可以看代码细节
每个(或者每组)可以隐藏的view 都对应有一个group view(group其实就是包含了view和spacing) 需要隐藏的时候 直接隐藏这个group 就可以达到既隐藏view又缩短间隙的目的
代码较长 大家可以选择跳过 - -!
@interface ComplexCell()
@property (nonatomic, strong) MASConstraint *cF; //constraint first row
@property (nonatomic, strong) MASConstraint *cB; //constraint blue
@property (nonatomic, strong) MASConstraint *cY; //constraint yellow
@property (nonatomic, strong) MASConstraint *cR; //constraint red
@property (nonatomic, strong) MASConstraint *cG; //constraint green
@property (nonatomic, strong) UIView *gF; //group first row
@property (nonatomic, strong) UIView *gB; //group blue
@property (nonatomic, strong) UIView *gY; //group yellow
@property (nonatomic, strong) UIView *gR; //group red
@property (nonatomic, strong) UIView *gG; //group green
@property (nonatomic, strong) UIView *vB; //view blue height:30
@property (nonatomic, strong) UIView *vY; //view yellow height:30
@property (nonatomic, strong) UIView *vR; //view red height:30
@property (nonatomic, strong) UIView *vG; //view green height:100
@end
@implementation ComplexCell
- (instancetype)initWithStyle:(UITableViewCellStyle)style reuseIdentifier:(NSString *)reuseIdentifier {
self = [super initWithStyle:style reuseIdentifier:reuseIdentifier];
if ( self ) {
CGFloat spacing = 20.0f;
self.gF = [UIView new];
[self.contentView addSubview:self.gF];
[self.gF mas_makeConstraints:^(MASConstraintMaker *make) {
make.left.top.right.equalTo(self.contentView);
self.cF = make.height.equalTo(@0).priority(UILayoutPriorityRequired);
[self.cF deactivate];
}];
self.gF.clipsToBounds = YES;
self.gB = [UIView new];
[self.gF addSubview:self.gB];
[self.gB mas_makeConstraints:^(MASConstraintMaker *make) {
make.left.top.bottom.equalTo(self.gF);
self.cB = make.width.equalTo(@0).priority(UILayoutPriorityRequired);
[self.cB deactivate];
}];
self.gB.clipsToBounds = YES;
self.gY = [UIView new];
[self.gF addSubview:self.gY];
[self.gY mas_makeConstraints:^(MASConstraintMaker *make) {
make.right.top.bottom.equalTo(self.gF);
make.left.equalTo(self.gB.mas_right);
self.cY = make.width.equalTo(@0).priority(UILayoutPriorityRequired);
[self.cY deactivate];
}];
self.gY.clipsToBounds = YES;
self.gR = [UIView new];
[self.contentView addSubview:self.gR];
[self.gR mas_makeConstraints:^(MASConstraintMaker *make) {
make.left.right.equalTo(self.contentView);
make.top.equalTo(self.gF.mas_bottom);
self.cR = make.height.equalTo(@0).priority(UILayoutPriorityRequired);
[self.cR deactivate];
}];
self.gR.clipsToBounds = YES;
self.gG = [UIView new];
[self.contentView addSubview:self.gG];
[self.gG mas_makeConstraints:^(MASConstraintMaker *make) {
make.left.right.equalTo(self.contentView);
make.top.equalTo(self.gR.mas_bottom);
self.cG = make.height.equalTo(@0).priority(UILayoutPriorityRequired);
[self.cG deactivate];
}];
self.gG.clipsToBounds = YES;
self.vB = [UIView new];
[self.gB addSubview:self.vB];
[self.vB mas_makeConstraints:^(MASConstraintMaker *make) {
make.edges.equalTo(self.gB).insets(UIEdgeInsetsMake(spacing, spacing, 0, 0)).priorityLow();
make.height.equalTo(@30);
make.width.equalTo(@60);
}];
self.vB.backgroundColor = [UIColor blueColor];
self.vY = [UIView new];
[self.gY addSubview:self.vY];
[self.vY mas_makeConstraints:^(MASConstraintMaker *make) {
make.edges.equalTo(self.gY).insets(UIEdgeInsetsMake(spacing, spacing, 0, spacing)).priorityLow();
make.height.equalTo(@30);
}];
self.vY.backgroundColor = [UIColor yellowColor];
self.vR = [UIView new];
[self.gR addSubview:self.vR];
[self.vR mas_makeConstraints:^(MASConstraintMaker *make) {
make.edges.equalTo(self.gR).insets(UIEdgeInsetsMake(spacing, spacing, 0, spacing)).priorityLow();
make.height.equalTo(@30);
}];
self.vR.backgroundColor = [UIColor redColor];
self.vG = [UIView new];
[self.gG addSubview:self.vG];
[self.vG mas_makeConstraints:^(MASConstraintMaker *make) {
make.edges.equalTo(self.gG).insets(UIEdgeInsetsMake(spacing, spacing, 0, spacing)).priorityLow();
make.height.equalTo(@100);
}];
self.vG.backgroundColor = [UIColor greenColor];
[self.cF deactivate];
[self.cB deactivate];
[self.cY deactivate];
[self.cR deactivate];
[self.cG deactivate];
}
return self;
}
然后 为每种不同的布局定义一个枚举(为了举例我随便定义的 0和1代表这个view是否被显示)
typedef NS_ENUM(NSUInteger, ComplexType) {
ComplexType1111,
ComplexType1110,
ComplexType0111,
ComplexType0011,
ComplexType0010,
ComplexType1101
};
@interface ComplexCell : UITableViewCell
@property (nonatomic, assign) ComplexType type;
+ (CGFloat) getHeightByType:(ComplexType)type;
@end
- (void)setType:(ComplexType)type {
[self.cF deactivate];
[self.cB deactivate];
[self.cY deactivate];
[self.cR deactivate];
[self.cG deactivate];
switch (type) {
case ComplexType1111:
{
break;
}
case ComplexType0111:
{
[self.cB activate];
break;
}
case ComplexType0011:
{
[self.cF activate];
break;
}
case ComplexType1110:
{
[self.cG activate];
break;
}
case ComplexType1101:
{
[self.cR activate];
break;
}
case ComplexType0010:
{
[self.cF activate];
[self.cG activate];
break;
}
default:
break;
}
}
这样 在tableview的datasource中我们只要这样做就可以了
- (NSInteger)numberOfSectionsInTableView:(UITableView *)tableView {
return 1;
}
- (NSInteger)tableView:(UITableView *)tableView numberOfRowsInSection:(NSInteger)section {
return 6;
}
- (CGFloat)tableView:(UITableView *)tableView heightForRowAtIndexPath:(NSIndexPath *)indexPath {
return [ComplexCell getHeightByType:indexPath.row%6];
}
- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath {
ComplexCell* cell = [tableView dequeueReusableCellWithIdentifier:@"cell"];
cell.type = indexPath.row%6;
return cell;
}
看看效果 是不是很不错
小结
文中的demo可以 在这里找到 要注意的地方是约束的priority的设置 另外 这种方式也支持不定长内容的Autolayout
可能很多人看了觉得我在瞎折腾 明明一个挺简单实现的东西 被我一弄 弄得又长又臭 其实不然 像我这种方法虽然麻烦了点(文章开头就指出了) 但是面对稍微复杂点的需求 却是更得心应手
使用group的方式 面对同时在横向和纵向都有隐藏要求的时候 会方便很多比如文中举的例子 第一行有时会隐藏蓝色的按钮 有时整个一行都会不显示 这样的话 当我想隐藏按钮时 只要激活按钮的约束 想隐藏整行时 只要激活整行的那条约束就行了
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