Ios 如何在UIButton'；s尺码合适/尺码合适？

我发现sizeToFit或SizeToFits将更改

ui按钮的当前宽度

UIButton* btn = [UIButton buttonWithType:UIButtonTypeCustom];
btn.frame = CGRectMake(100, 100, 200, 40);
btn.backgroundColor = [UIColor redColor];
[btn.titleLabel setText:@"ssdkfjsakdfjsakfjaksdjfkasjfkasjkfasjkfsajfkasjkas"];
btn.titleLabel.numberOfLines = 0;
[btn setTitle:@"ssdkfjsakdfjsakfjaksdjfkasjfkasjkfasjkfsajfkasjkas" forState:UIControlStateNormal];
[self.view addSubview:btn];

NSLog(@"before sizeToFit: %@",NSStringFromCGRect(btn.frame));
CGSize size = [btn sizeThatFits:CGSizeMake(200, 1000)];
[btn sizeToFit];

NSLog(@"after sizeToFit:%@",NSStringFromCGRect(btn.frame));
NSLog(@" sizeThatFits:%@",NSStringFromCGSize(size));

输出将是：

before sizeToFit: {{100, 100}, {200, 40}}
after sizeToFit:{{100, 100}, {392, 34}}
sizeThatFits:{392, 34}

这不是我想要的行为，如果我想要sizeToFit根据其原点宽度将按钮框调整到适当的高度。如何做到这一点
 如果要更改sizeToFit设置的大小，需要重写SizeToFits方法。创建
UIButton
的子类，如下所示：

斯威夫特：
目标C：
并使用子类按钮而不是UIButton

UIButton* btn = [MyButton buttonWithType:UIButtonTypeCustom];

参考：

@implementation MyButton

- (CGSize)sizeThatFits:(CGSize)size {
    CGSize sizeThatFits = [super sizeThatFits:size];
    return CGSizeMake(sizeThatFits.width, self.frame.size.height);
}

@end

UIButton* btn = [MyButton buttonWithType:UIButtonTypeCustom];