fix multi-line UILabel

AutoLayoutFixLabel.m

// iOS8之下，Auto Layout中使用多行Label的时候，需要手工设置preferredMaxLayoutWidth才能work，iOS8之后则不需要;
// 最低支持版本变为iOS8的时候，改用UILabel即可
// 1. http://stackoverflow.com/questions/25398312/automatic-preferred-max-layout-width-is-not-available-on-ios-versions-prior-to-8
// 2. http://stackoverflow.com/questions/17491376/ios-autolayout-multi-line-uilabel
#if (defined(__IPHONE_OS_VERSION_MIN_REQUIRED) && __IPHONE_OS_VERSION_MIN_REQUIRED < __IPHONE_8_0)
@interface AutolayoutFixLabel : UILabel
@end
#endif
 
#if (defined(__IPHONE_OS_VERSION_MIN_REQUIRED) && __IPHONE_OS_VERSION_MIN_REQUIRED < __IPHONE_8_0)
@implementation AutolayoutFixLabel
 
- (void)setBounds:(CGRect)bounds
{
    if ([[[UIDevice currentDevice] systemVersion] floatValue] < 7.99) {
        self.preferredMaxLayoutWidth = bounds.size.width;
    }
    [super setBounds:bounds];
}
@end
#endif