自定义UILabel，设置内边距

系统的UILabel附上文字后后自动给出一定的内边距，按照UI的设计图需求，标签附着文字后不能留有边距，只能自己自定义一个没有内边距的UILabel。

---

OC版本

#import 
IB_DESIGNABLE
@interface InsetLabel : UILabel
@property (nonatomic, assign) IBInspectable CGFloat leftEdge;
@property (nonatomic, assign) IBInspectable CGFloat rightEdge;
@property (nonatomic, assign) IBInspectable CGFloat topEdge;
@property (nonatomic, assign) IBInspectable CGFloat bottomEdge;
@property (nonatomic, assign) UIEdgeInsets edgeInsets;
@end

#import "InsetLabel.h"
@implementation InsetLabel

- (id)initWithFrame:(CGRect)frame {
    self = [super initWithFrame:frame];
    if (self) {
        self.edgeInsets = UIEdgeInsetsMake(self.topEdge, self.leftEdge, self.bottomEdge, self.rightEdge);
    }
    return self;
}
// 文字区域
- (void)drawTextInRect:(CGRect)rect {
    self.edgeInsets = UIEdgeInsetsMake(self.topEdge, self.leftEdge, self.bottomEdge, self.rightEdge);
    [super drawTextInRect:UIEdgeInsetsInsetRect(rect, self.edgeInsets)];
}
// UILabel的内容区域
- (CGSize)intrinsicContentSize {
    self.edgeInsets = UIEdgeInsetsMake(self.topEdge, self.leftEdge, self.bottomEdge, self.rightEdge);
    CGSize size = [super intrinsicContentSize];
    size.width  += self.edgeInsets.left + self.edgeInsets.right;
    size.height += self.edgeInsets.top + self.edgeInsets.bottom;
    return size;
}
@end

---

swift版本

class UILabelPadding : UILabel {

    private var padding = UIEdgeInsetsZero

    @IBInspectable
    var paddingLeft: CGFloat {
        get { return padding.left }
        set { padding.left = newValue }
    }

    @IBInspectable
    var paddingRight: CGFloat {
        get { return padding.right }
        set { padding.right = newValue }
    }

    @IBInspectable
    var paddingTop: CGFloat {
        get { return padding.top }
        set { padding.top = newValue }
    }

    @IBInspectable
    var paddingBottom: CGFloat {
        get { return padding.bottom }
        set { padding.bottom = newValue }
    }


    // 文字区域
    override func drawTextInRect(rect: CGRect) {
        super.drawTextInRect(UIEdgeInsetsInsetRect(rect, padding))

    }

    // UILabel的内容区域
    override func textRectForBounds(bounds: CGRect, limitedToNumberOfLines numberOfLines: Int) -> CGRect {
        let insets = self.padding
        var rect = super.textRectForBounds(UIEdgeInsetsInsetRect(bounds, insets), limitedToNumberOfLines: numberOfLines)
        rect.origin.x    -= insets.left
        rect.origin.y    -= insets.top
        rect.size.width  += (insets.left + insets.right)
        rect.size.height += (insets.top + insets.bottom)
        return rect
    }
}