只為探究日常開(kāi)發(fā)過(guò)程中可能會(huì)出現(xiàn)的離屏渲染

本次實(shí)驗(yàn)僅探究使用cornerRadius & masksToBounds 切圓角

查看離屏渲染設(shè)置 - 發(fā)生離屏渲染時(shí)背景顏色為黃色

1、切圓角是否一定會(huì)觸發(fā)離屏渲染 - 多組對(duì)照實(shí)驗(yàn)（以下代碼都可以拿去自己嘗試，事實(shí)不會(huì)騙人）

    /// 第一組 不存在子view時(shí)
    /// 結(jié)論不會(huì)觸發(fā)離屏渲染
    UIView *parentView = [[UIView alloc] init];
    parentView.layer.cornerRadius = 50;
    parentView.layer.masksToBounds = YES;
    parentView.frame = CGRectMake(0, 100, 100, 100);
    [self.view addSubview:parentView];

    /// 第二組存在子view時(shí)
    /// 結(jié)論不會(huì)觸發(fā)離屏渲染
    UIView *parentView = [[UIView alloc] init];
    parentView.layer.cornerRadius = 50;
    parentView.layer.masksToBounds = YES;
    parentView.frame = CGRectMake(0, 100, 100, 100);
    [self.view addSubview:parentView];

    UIView *childrenView = [[UIView alloc] init];
    childrenView.frame = CGRectMake(0, 0, 40, 40);
    [parentView addSubview:childrenView];

    /// 第三組存在子view時(shí),parentView存在背景色
    /// 結(jié)論不會(huì)觸發(fā)離屏渲染
    UIView *parentView = [[UIView alloc] init];
    parentView.backgroundColor = [UIColor redColor];
    parentView.layer.cornerRadius = 50;
    parentView.layer.masksToBounds = YES;
    parentView.frame = CGRectMake(0, 100, 100, 100);
    [self.view addSubview:parentView];

    UIView *childrenView = [[UIView alloc] init];
    childrenView.frame = CGRectMake(0, 0, 40, 40);
    [parentView addSubview:childrenView];

    /// 第四組存在子view時(shí)，parentView和子view同時(shí)存在背景色
    /// 結(jié)論會(huì)觸發(fā)離屏渲染
    UIView *parentView = [[UIView alloc] init];
    parentView.backgroundColor = [UIColor redColor];
    parentView.layer.cornerRadius = 50;
    parentView.layer.masksToBounds = YES;
    parentView.frame = CGRectMake(0, 100, 100, 100);
    [self.view addSubview:parentView];

    UIView *childrenView = [[UIView alloc] init];
    childrenView.frame = CGRectMake(0, 0, 40, 40);
    childrenView.backgroundColor = [UIColor blackColor];
    [parentView addSubview:childrenView];

    /// 第五組存在子view時(shí)蒿柳，僅子View背景色存在崖蜜，且被切割到
    /// 結(jié)論會(huì)觸發(fā)離屏渲染
    UIView *parentView = [[UIView alloc] init];
    parentView.layer.cornerRadius = 50;
    parentView.layer.masksToBounds = YES;
    parentView.frame = CGRectMake(0, 100, 100, 100);
    [self.view addSubview:parentView];

    UIView *childrenView = [[UIView alloc] init];
    childrenView.frame = CGRectMake(0, 0, 40, 40);
    childrenView.backgroundColor = [UIColor blackColor];
    [parentView addSubview:childrenView];

    /// 第六組存在子view時(shí)乒疏，僅子View存在背景色且子View不被切割
    /// 結(jié)論不會(huì)觸發(fā)離屏渲染
    UIView *parentView = [[UIView alloc] init];
    parentView.layer.cornerRadius = 50;
    parentView.layer.masksToBounds = YES;
    parentView.frame = CGRectMake(0, 100, 100, 100);
    [self.view addSubview:parentView];

    UIView *childrenView = [[UIView alloc] init];
    childrenView.frame = CGRectMake(25, 25, 40, 40);
    childrenView.backgroundColor = [UIColor blackColor];
    [parentView addSubview:childrenView];

    /// 第七組存在子view時(shí)盖高，父view和子View同時(shí)存在背景色且子View不被切割
    /// 結(jié)論會(huì)觸發(fā)離屏渲染
    UIView *parentView = [[UIView alloc] init];
    parentView.backgroundColor = [UIColor redColor];
    parentView.layer.cornerRadius = 50;
    parentView.layer.masksToBounds = YES;
    parentView.frame = CGRectMake(0, 100, 100, 100);
    [self.view addSubview:parentView];

    UIView *childrenView = [[UIView alloc] init];
    childrenView.frame = CGRectMake(25, 25, 40, 40);
    childrenView.backgroundColor = [UIColor blackColor];
    [parentView addSubview:childrenView];

    /// 第八組存在子view時(shí)听想，父view和子View同時(shí)存在背景色且相同邦马，且子View不被切割
    /// 結(jié)論會(huì)觸發(fā)離屏渲染
    UIView *parentView = [[UIView alloc] init];
    parentView.backgroundColor = [UIColor redColor];
    parentView.layer.cornerRadius = 50;
    parentView.layer.masksToBounds = YES;
    parentView.frame = CGRectMake(0, 100, 100, 100);
    [self.view addSubview:parentView];

    UIView *childrenView = [[UIView alloc] init];
    childrenView.frame = CGRectMake(25, 25, 40, 40);
    childrenView.backgroundColor = [UIColor redColor];
    [parentView addSubview:childrenView];

通過(guò)上述實(shí)驗(yàn)得到結(jié)論如下：
1贱鼻、通過(guò)1、2組實(shí)驗(yàn)得出滋将，存在子View并切割子View時(shí)不一定會(huì)出現(xiàn)離屏渲染
2邻悬、通過(guò)3、4随闽、7父丰、8組實(shí)驗(yàn)得出，存在子View且同時(shí)存在顏色時(shí)一定會(huì)出現(xiàn)離屏渲染
3掘宪、通過(guò)5蛾扇、6組實(shí)驗(yàn)得出，僅子View存在背景顏色且被切割時(shí)一定會(huì)出現(xiàn)離屏渲染

總結(jié)：在不設(shè)置背景色時(shí)圓角放心大膽切魏滚，如果子View存在背景色僅一種情況不會(huì)出現(xiàn)離屏渲染镀首，就是不切割到子View且父View不存在背景顏色

2、可能存在遺漏的實(shí)驗(yàn)組鼠次，辛苦大家留言區(qū)補(bǔ)充更哄，盡量第一時(shí)間更新