先理解下面 （不理解也行，会调用就可以）
Button有两个属性：titleEdgeInsets和imageEdgeInsets，通过设置这两个，就可以实现所有需要的Button的样式，如：image在上、image在下、image在左、image在右。
titleEdgeInsets是titleLabel相对于其上下左右的inset，跟tableView的contentInset是类似的；
如果只有title，那titleLabel的上下左右都是相对于Button的；
如果只有image，那imageView的上下左右都是相对于Button的；
如果同时有image和label，那image的上下左是相对于Button的，右是相对于label的；
label的上下右是相对于Button的，左是相对于label的。
写一个UIbutton的分类
.h文件
#importtypedef NS_ENUM(NSUInteger, MKButtonEdgeInsetsStyle) {
MKButtonEdgeInsetsStyleTop, // image在上，label在下
MKButtonEdgeInsetsStyleLeft, // image在左，label在右
MKButtonEdgeInsetsStyleBottom, // image在下，label在上
MKButtonEdgeInsetsStyleRight // image在右，label在左
};
@interface UIButton (ImageTitleSpacing)
/**
* 设置button的titleLabel和imageView的布局样式，及间距
*
* @param style titleLabel和imageView的布局样式
* @param space titleLabel和imageView的间距
*/
- (void)layoutButtonWithEdgeInsetsStyle:(MKButtonEdgeInsetsStyle)style
imageTitleSpace:(CGFloat)space;
@end
.m 文件
#import "UIButton+ImageTitleSpacing.h"
@implementation UIButton (ImageTitleSpacing)
- (void)layoutButtonWithEdgeInsetsStyle:(MKButtonEdgeInsetsStyle)style
imageTitleSpace:(CGFloat)space
{
// self.backgroundColor = [UIColor cyanColor];
/**
* 前置知识点：titleEdgeInsets是title相对于其上下左右的inset，跟tableView的contentInset是类似的，
* 如果只有title，那它上下左右都是相对于button的，image也是一样；
* 如果同时有image和label，那这时候image的上左下是相对于button，右边是相对于label的；title的上右下是相对于button，左边是相对于image的。
*/
// 1. 得到imageView和titleLabel的宽、高
CGFloat imageWith = [UIDevice currentDevice].systemVersion.floatValue >= 8.0?self.imageView.intrinsicContentSize.width:self.imageView.frame.size.width;
CGFloat imageHeight = [UIDevice currentDevice].systemVersion.floatValue >= 8.0?self.imageView.intrinsicContentSize.height:self.imageView.frame.size.height;
CGFloat labelWidth = 0.0;
CGFloat labelHeight = 0.0;
if ([UIDevice currentDevice].systemVersion.floatValue >= 8.0) {
// 由于iOS8中titleLabel的size为0，用下面的这种设置
labelWidth = self.titleLabel.intrinsicContentSize.width;
labelHeight = self.titleLabel.intrinsicContentSize.height;
} else {
labelWidth = self.titleLabel.frame.size.width;
labelHeight = self.titleLabel.frame.size.height;
}
// 2. 声明全局的imageEdgeInsets和labelEdgeInsets
UIEdgeInsets imageEdgeInsets = UIEdgeInsetsZero;
UIEdgeInsets labelEdgeInsets = UIEdgeInsetsZero;
// 3. 根据style和space得到imageEdgeInsets和labelEdgeInsets的值
switch (style) {
case MKButtonEdgeInsetsStyleTop:
{
imageEdgeInsets = UIEdgeInsetsMake(-labelHeight-space/2.0, 0, 0, -labelWidth);
labelEdgeInsets = UIEdgeInsetsMake(0, -imageWith, -imageHeight-space/2.0, 0);
}
break;
case MKButtonEdgeInsetsStyleLeft:
{
imageEdgeInsets = UIEdgeInsetsMake(0, -space/2.0, 0, space/2.0);
labelEdgeInsets = UIEdgeInsetsMake(0, space/2.0, 0, -space/2.0);
}
break;
case MKButtonEdgeInsetsStyleBottom:
{
imageEdgeInsets = UIEdgeInsetsMake(0, 0, -labelHeight-space/2.0, -labelWidth);
labelEdgeInsets = UIEdgeInsetsMake(-imageHeight-space/2.0, -imageWith, 0, 0);
}
break;
case MKButtonEdgeInsetsStyleRight:
{
imageEdgeInsets = UIEdgeInsetsMake(0, labelWidth+space/2.0, 0, -labelWidth-space/2.0);
labelEdgeInsets = UIEdgeInsetsMake(0, -imageWith-space/2.0, 0, imageWith+space/2.0);
}
break;
default:
break;
}
// 4. 赋值
self.titleEdgeInsets = labelEdgeInsets;
self.imageEdgeInsets = imageEdgeInsets;
}
@end
调用的话就很简单了，以图片在上，title在下为例子
MKButtonEdgeInsetsStyleTop, // image在上，label在下
MKButtonEdgeInsetsStyleLeft, // image在左，label在右
MKButtonEdgeInsetsStyleBottom, // image在下，label在上
MKButtonEdgeInsetsStyleRight // image在右，label在左
调用：
CGRect frame = CGRectMake(x, y, width, height);
UIButton *button = [[UIButton alloc] initWithFrame:frame];
[button layoutButtonWithEdgeInsetsStyle:MKButtonEdgeInsetsStyleTop imageTitleSpace:1.0];
