自定义导航栏的返回按钮，扩大点击区域，不改变图片的尺寸比例，同时可设置title和image的位置关系

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自定义导航栏的左侧按钮，同时可扩大button的点击区域，不改变图片的尺寸比例，设置title和image的位置关系。默认是居中。

UIButton * btn = [UIButton buttonWithType:UIButtonTypeCustom];

btn.frame = CGRectMake(0, 0, 100, 44);

[btn setImage:[UIImage imageNamed:@"返回icon1.png"] forState:UIControlStateNormal];//40*32图片尺寸大小
btn.imageEdgeInsets = UIEdgeInsetsMake(0,
-50, 0, 0);//设置偏移量

[btn addTarget:self action:@selector(goBackPage:) forControlEvents:UIControlEventTouchUpInside];

UIBarButtonItem * leftItem = [[UIBarButtonItem alloc]initWithCustomView:btn];

self.navigationItem.leftBarButtonItem =
leftItem;

UIEdgeInsetsMake

里面的四个参数表示距离上边界、左边界、下边界、右边界的距离，默认都为零，title／image在button的正中央

[objc]

UIKIT_STATIC_INLINE UIEdgeInsets UIEdgeInsetsMake(CGFloat top, CGFloat left, CGFloat bottom, CGFloat right) {

UIEdgeInsets insets = {top, left, bottom, right};

return insets;

}

[objc]

self.view.backgroundColor = [UIColor blackColor];

UIButton *button = [UIButton buttonWithType:UIButtonTypeCustom];//button的类型

button.frame = CGRectMake(100, 100,90, 90);//button的frame

button.backgroundColor = [UIColor cyanColor];//button的背景颜色

// [button setBackgroundImage:[UIImage imageNamed:@"man_64.png"] forState:UIControlStateNormal];

// 在UIButton中有三个对EdgeInsets的设置：ContentEdgeInsets、titleEdgeInsets、imageEdgeInsets

[button setImage:[UIImage imageNamed:@"IconHome@2x.png"] forState:UIControlStateNormal];//给button添加image

button.imageEdgeInsets = UIEdgeInsetsMake(5,13,21,button.titleLabel.bounds.size.width);//设置image在button上的位置（上top，左left，下bottom，右right）这里可以写负值，对上写－5，那么image就象上移动5个像素

[button setTitle:@"首页" forState:UIControlStateNormal];//设置button的title

button.titleLabel.font = [UIFont systemFontOfSize:16];//title字体大小

button.titleLabel.textAlignment = NSTextAlignmentCenter;//设置title的字体居中

[button setTitleColor:[UIColor whiteColor] forState:UIControlStateNormal];//设置title在一般情况下为白色字体

[button setTitleColor:[UIColor grayColor] forState:UIControlStateHighlighted];//设置title在button被选中情况下为灰色字体

button.titleEdgeInsets = UIEdgeInsetsMake(71, -button.titleLabel.bounds.size.width-50, 0, 0);//设置title在button上的位置（上top，左left，下bottom，右right）

// [button setContentEdgeInsets:UIEdgeInsetsMake(70, 0, 0, 0)];//

// button.contentHorizontalAlignment = UIControlContentHorizontalAlignmentCenter;//设置button的内容横向居中。。设置content是title和image一起变化

[button addTarget:self action:@selector(tap) forControlEvents:UIControlEventTouchUpInside];

[self.view addSubview:button];

[objc]

//button相应的事件

-(void)tap {

NSLog(@"tap a button");

UIAlertView *alertView = [[UIAlertView alloc] initWithTitle:@"hello" message:@"willingseal" delegate:self cancelButtonTitle:@"ok" otherButtonTitles: nil nil];

[alertView show];

}