在OC中是不能UI元素.位置/大小属性 = XXX这种形式直接赋值的，所以需要给UIView建立分类才能实现上述赋值方法；
而在Swift中，是可以对元素的大小/位置属性直接赋值的，但是也要写很长一串，Swift也可通过建立分类达到和OC一样的效果。

在这里只列出：origin、size、x、y、width、height、centerX、centerY的赋值写法

• OC版本（需要在.h中声明对应属性）

- (void)setWidth:(CGFloat)width
{
    CGRect frame = self.frame;
    frame.size.width = width;
    self.frame = frame;
}
- (void)setHeight:(CGFloat)height
{
    CGRect frame = self.frame;
    frame.size.height = height;
    self.frame = frame;
}
- (void)setX:(CGFloat)x
{
    CGRect frame = self.frame;
    frame.origin.x = x;
    self.frame = frame;
}
- (void)setY:(CGFloat)y
{
    CGRect frame = self.frame;
    frame.origin.y = y;
    self.frame = frame;
}
- (void)setSize:(CGSize)size
{
    CGRect frame = self.frame;
    frame.size = size;
    self.frame = frame;
}
- (void)setCenterX:(CGFloat)centerX
{
    CGPoint center = self.center;
    center.x = centerX;
    self.center = center;
}
- (void)setCenterY:(CGFloat)centerY
{
    CGPoint center = self.center;
    center.y = centerY;
    self.center = center;
}

- (CGFloat)centerX
{
    return self.center.x;
}
- (CGFloat)centerY
{
    return self.center.y;
}

-(CGSize)size
{
    return self.frame.size;
}

-(CGFloat)width
{
    return self.frame.size.width;
}
-(CGFloat)height
{
    return self.frame.size.height;
}
-(CGFloat)x
{
    return self.frame.origin.x;
}
-(CGFloat)y
{
    return self.frame.origin.y;
}

- (CGPoint)origin {
    return self.frame.origin;
}

- (void)setOrigin:(CGPoint)origin {
    CGRect frame = self.frame;
    frame.origin = origin;
    self.frame = frame;
}

• Swift版本（此段写于 2016/12/16 适用于swift 3.0）：

public var x : CGFloat {
        get {
            return self.frame.origin.x
        }
        set {
            var f = self.frame
            f.origin.x = newValue
            self.frame = f
        }
    }
    /// y
    public var y : CGFloat {
        get {
            return self.frame.origin.y
        }
        set {
            var f = self.frame
            f.origin.y = newValue
            self.frame = f
        }
    }
    /// width
    public var width : CGFloat {
        get {
            return self.frame.size.width
        }
        set {
            var f = self.frame
            f.size.width = newValue
            self.frame = f
        }
    }
    /// height
    public var height : CGFloat {
        get {
            return self.frame.size.height
        }
        set {
            var f = self.frame
            f.size.height = newValue
            self.frame = f
        }
    }
    /// origin
    public var origin : CGPoint {
        get {
            return self.frame.origin
        }
        set {
            var f = self.frame
            f.origin = newValue
            self.frame = f
        }
    }
    /// size 
    public var size : CGSize {
        get {
            return self.frame.size
        }
        set {
            var f = self.frame
            f.size = newValue
            self.frame = f
        }
    }
    /// centerX
    public var centerX : CGFloat {
        get {
            return self.center.x
        }
        set {
            var c = self.center
            c.x = newValue
            self.center = c
        }
    }
    /// centerY
    public var centerY : CGFloat {
        get {
            return self.center.y
        }
        set {
            var c = self.center
            c.y = newValue
            self.center = c
        }
    }