Mac_NSLayout

使用NSLayout对控件进行布局，这个如果放到iOS中我是有自己写的一套控件布局的工具类。好多人都在用第三方的masry但是我没有选择用，因为第三方库中会有许多自己用不到的东西。如果出现问题有时候也不好处理。在mac os开发中使用NSLayout也是一次自己的尝试。
我这里有三个 nsview。布局如下

- (void)addTowButton {    self.towButton = [[NSView alloc]init];    [self.towButton setWantsLayer:YES];    self.towButton.layer.backgroundColor = [NSColor purpleColor].CGColor;    // 禁止将 AutoresizingMask转换为Constraints    self.towButton.translatesAutoresizingMaskIntoConstraints = NO;    [self.window.contentView addSubview:self.towButton];      // 添加width约束    NSLayoutConstraint *width = [NSLayoutConstraint constraintWithItem:self.towButton attribute:NSLayoutAttributeWidth relatedBy:NSLayoutRelationEqual toItem:nil attribute:NSLayoutAttributeNotAnAttribute multiplier:0.0 constant:150];    [self.towButton addConstraint:width];    // 添加height约束    NSLayoutConstraint *height = [NSLayoutConstraint constraintWithItem:self.towButton attribute:NSLayoutAttributeHeight relatedBy:NSLayoutRelationEqual toItem:nil attribute:NSLayoutAttributeNotAnAttribute multiplier:0.0 constant:150];    [self.towButton addConstraint:height];    // 添加left约束    NSLayoutConstraint *left = [NSLayoutConstraint constraintWithItem:self.towButton attribute:NSLayoutAttributeLeft relatedBy:NSLayoutRelationEqual toItem:self.window.contentView attribute:(NSLayoutAttributeLeft) multiplier:1.0 constant:100];    [self.window.contentView addConstraint:left];    // 添加top约束    NSLayoutConstraint *top = [NSLayoutConstraint constraintWithItem:self.towButton attribute:NSLayoutAttributeTop relatedBy:NSLayoutRelationEqual toItem:self.window.contentView attribute:NSLayoutAttributeTop multiplier:1.0 constant:30];    [self.window.contentView addConstraint:top];}

- (void)addAnother{    self.anotherButton = [[NSView alloc]init];    [self.anotherButton setWantsLayer:YES];    self.anotherButton.layer.backgroundColor = [NSColor redColor].CGColor;    self.anotherButton.translatesAutoresizingMaskIntoConstraints = NO;    [self.window.contentView addSubview:self.anotherButton];    // 设置约束    // 设置宽度    NSLayoutConstraint *width = [NSLayoutConstraint constraintWithItem:self.anotherButton attribute:NSLayoutAttributeWidth relatedBy:NSLayoutRelationEqual toItem:nil attribute:NSLayoutAttributeNotAnAttribute multiplier:0.0 constant:150];    [self.anotherButton addConstraint:width];    // 设置高度    NSLayoutConstraint *height = [NSLayoutConstraint constraintWithItem:self.anotherButton attribute:NSLayoutAttributeHeight relatedBy:NSLayoutRelationEqual toItem:nil attribute:NSLayoutAttributeNotAnAttribute multiplier:0.0 constant:150];    [self.anotherButton addConstraint:height];    // 设置左侧    NSLayoutConstraint *left = [NSLayoutConstraint constraintWithItem:self.anotherButton attribute:NSLayoutAttributeLeft relatedBy:NSLayoutRelationEqual toItem:self.towButton attribute:NSLayoutAttributeRight multiplier:1.0 constant:100];    [self.window.contentView addConstraint:left];    // 设置top    NSLayoutConstraint *top = [NSLayoutConstraint constraintWithItem:self.anotherButton attribute:NSLayoutAttributeTop relatedBy:NSLayoutRelationEqual toItem:self.window.contentView attribute:NSLayoutAttributeTop multiplier:1.0 constant:50];    [self.window.contentView addConstraint:top];}

- (void)addLowLayout {    self.lowButton = [[NSView alloc]init];    [self.lowButton setWantsLayer:YES];    self.lowButton.layer.backgroundColor = [NSColor greenColor].CGColor;    self.lowButton.translatesAutoresizingMaskIntoConstraints = NO;    [self.window.contentView addSubview:self.lowButton];    // align layer from the width    NSLayoutConstraint *width = [NSLayoutConstraint constraintWithItem:self.lowButton attribute:NSLayoutAttributeWidth relatedBy:NSLayoutRelationEqual toItem:nil attribute:NSLayoutAttributeNotAnAttribute multiplier:0.0 constant:self.window.frame.size.width / 3];    [self.lowButton addConstraint:width];    // align layer from the height    [self.lowButton addConstraint:[NSLayoutConstraint constraintWithItem:self.lowButton attribute:NSLayoutAttributeHeight relatedBy:NSLayoutRelationEqual toItem:nil attribute:NSLayoutAttributeNotAnAttribute multiplier:0.0 constant:self.window.frame.size.height / 3]];    // align layer from the left    [self.window.contentView addConstraint:[NSLayoutConstraint constraintWithItem:self.lowButton attribute:NSLayoutAttributeLeft relatedBy:NSLayoutRelationEqual toItem:self.window.contentView attribute:NSLayoutAttributeLeft multiplier:1.0 constant:100]];    // align layer from the top    [self.window.contentView addConstraint:[NSLayoutConstraint constraintWithItem:self.lowButton attribute:NSLayoutAttributeTop relatedBy:NSLayoutRelationEqual toItem:self.towButton attribute:NSLayoutAttributeBottom multiplier:1.0 constant:100]];}