po [self.view recursiveDescription]，打印分析视图的层级
1,
在PCH文件中添加以下代码,来判断当前工程的版本号
#if DEBUG
#define NSLog(...) NSLog(__VA_ARGS__)
#else
#define NSLog(...)
#endif
#ifdef DEBUG
#define DMLog(...) NSLog(@"%s %@", __PRETTY_FUNCTION__, [NSString stringWithFormat:__VA_ARGS__])
#else
#define DMLog(...) do { } while (0)
#endif
2,
真机运行,,只需要修改证书和Bundle Identifier
ScrollView莫名其妙不能在viewController划到顶怎么办？
self.automaticallyAdjustsScrollViewInsets = NO;
TableView不显示没内容的Cell怎么办？
self.tableView.tableFooterView = [[UIView alloc] init];
怎么像Safari一样滑动的时候隐藏navigationbar？
navigationController.hidesBarsOnSwipe = Yes
导航条返回键带的title太讨厌了，怎么让它消失？
[[UIBarButtonItem appearance] setBackButtonTitlePositionAdjustment:UIOffsetMake(0, -60)
forBarMetrics:UIBarMetricsDefault];
拉伸图片的时候怎么才能让图片不变形？
UIImage *image = [[UIImage imageNamed:@"xxx"] stretchableImageWithLeftCapWidth:10 topCapHeight:10];resizableImageWithCapInsets
自定义了leftBarbuttonItem左滑返回手势失效了怎么办？
self.navigationItem.leftBarButtonItem = [[UIBarButtonItem alloc]
initWithImage:img style:UIBarButtonItemStylePlain target:self action:@selector(onBack:)];
self.navigationController.interactivePopGestureRecognizer.delegate = (id<UIGestureRecognizerDelegate>)self;
怎么改变uitextfield placeholder的颜色和位置？
继承uitextfield，重写这个方法：
- (void) drawPlaceholderInRect:(CGRect)rect {
[[UIColor blueColor] setFill];
[self.placeholder drawInRect:rect withFont:self.font lineBreakMode:UILineBreakModeTailTruncation alignment:self.textAlignment];
}