动画绘制坐标系

思路一：利用Masonry约束x、y坐标的起始位置，在动画时间内改变x坐标轴的宽度和y坐标轴的高度。结果：坐标轴从屏幕左上角开始绘制，不是理想中的效果。代码如下：

//绘制坐标轴

- (void)drawCoordSystem{

    UIView *xCoord = [selfgetLine];

    UIView *yCoord = [selfgetLine];

    [xCoord mas_updateConstraints:^(MASConstraintMaker *make) {

        make.width.mas_equalTo(@(self.view.bounds.size.width - 20.0));

    }];

    

    [yCoord mas_updateConstraints:^(MASConstraintMaker *make) {

        make.height.mas_equalTo(@(self.view.bounds.size.height - 60));

    }];

    [self.viewsetNeedsUpdateConstraints];

    [self.viewupdateConstraintsIfNeeded];

    [UIViewanimateWithDuration:5.0animations:^{

        [self.viewlayoutIfNeeded];

    }];

}

//设置坐标轴起始位置

- (UIView *)getLine{

    UIView *lineView = [[UIViewalloc] init];

    [self.viewaddSubview:lineView];

    [lineView mas_makeConstraints:^(MASConstraintMaker *make) {

        make.left.equalTo(self.view).with.offset(10.0);

        make.bottom.equalTo(self.view).with.offset(-20.0);

        make.width.mas_equalTo(@(2.0));

        make.height.mas_equalTo(@(2.0));

    }];

    lineView.backgroundColor = [UIColorblackColor];

    lineView.alpha =0.618;

    return lineView;

}

思路二：通过计算确定x、y坐标轴的起始位置，动画改变宽度、高度。结果：坐标轴从左下角开始绘制，满足需求。代码如下：

- (void)drawCoordSystem{

    UIView *xLine = [self setLine];

    UIView *yLine = [self setLine];

    

    CGRect xRect = xLine.frame;

    CGRect yRect = yLine.frame;

    

    xRect.size.width = self.view.bounds.size.width - 20;

    yRect.size.height = self.view.bounds.size.height - 50;

    yRect.origin.y -= yRect.size.height;

    

    [UIView animateWithDuration:5.0 animations:^{

        xLine.frame = xRect;

        yLine.frame = yRect;

    }];

}

- (UIView *)setLine{

    UIView *lineView = [[UIView alloc] init];

    [self.view addSubview:lineView];

    

    CGFloat lineViewX = 10.0;

    CGFloat lineViewY = self.view.bounds.size.height - 20.0;

    CGFloat lineViewW = 2.0;

    CGFloat lineViewH = 2.0;

    

    lineView.frame = CGRectMake(lineViewX, lineViewY, lineViewW, lineViewH);

    

    lineView.backgroundColor = [UIColor blackColor];

    lineView.alpha = 0.618;

    

    return lineView;

}