iOS

---

资料

• raywenderlich
• onevcat

• iOS 6
  • 开发者所需要知道的iOS6 SDK新特性
• iOS 7
  • 开发者所需要知道的iOS7 SDK新特性
• iOS 8
  • 开发者所需要知道的 iOS8 SDK新特性
• iOS 9
  • 开发者所需要知道的 iOS9 SDK新特性
• iOS 10
  • 开发者所需要知道的 iOS10 SDK新特性
  • 兼容iOS 10 资料整理笔记
  • Swift3 改变收集
  • 今日头条iOS客户端启动速度优化

---

面试

• 上级向的十个iOS面试问题

---

Tips

• Swift打印内存地址

println(" str value \(str) has address: \(unsafeAddressOf(str))")

• Obj-C屏蔽警告

#pragma clang diagnostic push
#pragma clang diagnostic ignored "-Wdeprecated-declarations" 
...
#pragma clang diagnostic pop

• 打印代码文件中函数的调用过程

  clang -rewrite-objc xxx.m
  

• UIWebView获取Html标题

-(void)webViewDidFinishLoad:(UIWebView *)webView {    
    titleLabel.text = [webView stringByEvaluatingJavaScriptFromString:@"document.title"];
｝

• Category添加属性字段

@interface UIImage (category)
// 在UIImage中新建一个tag属性
@property (nonatomic, copy) NSString *tag;
@end

static const void *tagKey = &tagKey;
@implementation UIImage (category)
-(NSString *)tag { 
    return objc_getAssociatedObject(self, tagKey);
}
-(void)setTag:(NSString *)tag { 
    objc_setAssociatedObject(self, tagKey, tag, OBJC_ASSOCIATION_COPY_NONATOMIC);
}
@end

• 隐藏状态栏

override func prefersStatusBarHidden() -> Bool { return true }

• Runloop实现Alert同步弹窗

-(NSInteger)doModal {
    [self showAlert];
    _bModel = YES;
    while (_bModel) {
      [[NSRunLoop mainRunLoop] runMode:NSDefaultRunLoopMode beforeDate:[NSDate distantFuture]];
    }
    return _selectBtnIndex;
}
-(void)showAlert {
    UIAlertView *alertView = [[UIAlertView alloc] initWithTitle:@"" message:@"okookoko" delegate:self cancelButtonTitle:@"cancel" otherButtonTitles:@"ok", nil];
    [alertView show];
}
-(void)alertView:(UIAlertView *)alertView clickedButtonAtIndex:(NSInteger)buttonIndex {
    _selectBtnIndex = buttonIndex;
    _bModel = NO;
}

• UITableView的Group样式下顶部空白处理

//分组列表头部空白处理
UIView *view = [[UIView alloc] initWithFrame:CGRectMake(0, 0, 0, 0.1)];
self.tableView.tableHeaderView = view;

• 禁止锁屏

默认情况下，当设备一段时间没有触控动作时，iOS会锁住屏幕。但有一些应用是不需要锁屏的，比如视频播放器。

[UIApplication sharedApplication].idleTimerDisabled = YES;

• 模态推出透明界面

UIViewController *vc = [[UIViewController alloc] init];
UINavigationController *na = [[UINavigationController alloc] initWithRootViewController:vc];
if ([[[UIDevice currentDevice] systemVersion] floatValue] >= 8.0)
{
    na.modalPresentationStyle = UIModalPresentationOverCurrentContext;
} else {
    self.modalPresentationStyle=UIModalPresentationCurrentContext;
}
[self presentViewController:na animated:YES completion:nil];

• Xcode调试不显示内存占用

editSCheme 里面有个选项叫叫做enable zoombie Objects 取消选中

• 显示隐藏文件

//显示
defaults write com.apple.finder AppleShowAllFiles -bool true
killall Finder
//隐藏
defaults write com.apple.finder AppleShowAllFiles -bool false
killall Finder

• iOS跳转到App Store下载应用评分

[[UIApplication sharedApplication] openURL:[NSURL URLWithString:@"itms-apps://itunes.apple.com/WebObjects/MZStore.woa/wa/viewContentsUserReviews?type=Purple+Software&id=APPID"]];

• 手动更改iOS状态栏的颜色

-(void)setStatusBarBackgroundColor:(UIColor *)color
{
    UIView *statusBar = [[[UIApplication sharedApplication] valueForKey:@"statusBarWindow"] valueForKey:@"statusBar"];
    if ([statusBar respondsToSelector:@selector(setBackgroundColor:)])
    {
      statusBar.backgroundColor = color;
    }
}

• 获取实际使用的LaunchImage图片

-(NSString *)getLaunchImageName
{
    CGSize viewSize = self.window.bounds.size;
    // 竖屏
    NSString *viewOrientation = @"Portrait";
    NSString *launchImageName = nil;
    NSArray* imagesDict = [[[NSBundle mainBundle] infoDictionary] valueForKey:@"UILaunchImages"];
    for (NSDictionary* dict in imagesDict)
    {
        CGSize imageSize =     CGSizeFromString(dict[@"UILaunchImageSize"]);
        if (CGSizeEqualToSize(imageSize, viewSize) && [viewOrientation isEqualToString:dict[@"UILaunchImageOrientation"]])
        {
            launchImageName = dict[@"UILaunchImageName"];
        }
    }
    return launchImageName;
}

• 在当前屏幕获取第一响应

UIWindow * keyWindow = [[UIApplication sharedApplication] keyWindow];
UIView * firstResponder = [keyWindow performSelector:@selector(firstResponder)];

• 判断对象是否遵循了某协议

if ([self.selectedController conformsToProtocol:@protocol(RefreshPtotocol)])
{
    [self.selectedController performSelector:@selector(onTriggerRefresh)];
}

• 判断view是不是指定视图的子视图

BOOL isView = [textView isDescendantOfView:self.view];

• NSArray 快速求总和 最大值 最小值 和 平均值

NSArray *array = [NSArray arrayWithObjects:@"2.0", @"2.3", @"3.0", @"4.0", @"10", nil];
CGFloat sum = [[array valueForKeyPath:@"@sum.floatValue"] floatValue];
CGFloat avg = [[array valueForKeyPath:@"@avg.floatValue"] floatValue];
CGFloat max =[[array valueForKeyPath:@"@max.floatValue"] floatValue];
CGFloat min =[[array valueForKeyPath:@"@min.floatValue"] floatValue];
NSLog(@"%f\n%f\n%f\n%f",sum,avg,max,min);

• 修改UITextField中Placeholder的文字颜色

[textField setValue:[UIColor redColor] forKeyPath:@"_placeholderLabel.textColor"];

• 关于NSDateFormatter的格式

G: 公元时代，例如AD公元
yy: 年的后2位
yyyy: 完整年
MM: 月，显示为1-12
MMM: 月，显示为英文月份简写,如 Jan
MMMM: 月，显示为英文月份全称，如 Janualy
dd: 日，2位数表示，如02
d: 日，1-2位显示，如 2
EEE: 简写星期几，如Sun
EEEE: 全写星期几，如Sunday
aa: 上下午，AM/PM
H: 时，24小时制，0-23
K：时，12小时制，0-11
m: 分，1-2位
mm: 分，2位
s: 秒，1-2位
ss: 秒，2位
S: 毫秒

• 获取一个类的所有子类

+(NSArray *) allSubclasses
{
    Class myClass = [self class];
    NSMutableArray *mySubclasses = [NSMutableArray array];
    unsigned int numOfClasses;
    Class *classes = objc_copyClassList(&numOfClasses;);
    for (unsigned int ci = 0; ci < numOfClasses; ci++)
    {
        Class superClass = classes[ci];
        do{
            superClass = class_getSuperclass(superClass);
        } while (superClass && superClass != myClass);
        if (superClass)
        {
            [mySubclasses addObject: classes[ci]];
        }
    }
    free(classes);
    return mySubclasses;
}

• 监测设备是否设置了代理，需要CFNetwork.framework

NSDictionary *proxySettings = (__bridge NSDictionary *)(CFNetworkCopySystemProxySettings());
NSArray *proxies = (__bridge NSArray *)(CFNetworkCopyProxiesForURL((__bridge CFURLRef _Nonnull)([NSURL URLWithString:@"http://www.baidu.com"]), (__bridge CFDictionaryRef _Nonnull)(proxySettings)));
NSLog(@"\n%@",proxies);
NSDictionary *settings = proxies[0];
NSLog(@"%@",[settings objectForKey:(NSString *)kCFProxyHostNameKey]);
NSLog(@"%@",[settings objectForKey:(NSString *)kCFProxyPortNumberKey]);
NSLog(@"%@",[settings objectForKey:(NSString *)kCFProxyTypeKey]);
if ([[settings objectForKey:(NSString *)kCFProxyTypeKey] isEqualToString:@"kCFProxyTypeNone"])
{
NSLog(@"没代理");
}
else
{
NSLog(@"设置了代理");
}

• 取消UICollectionView的隐式动画

UICollectionView在reloadItems的时候，默认会附加一个隐式的fade动画，有时候很讨厌，尤其是当你的cell是复合cell的情况下(比如cell使用到了UIStackView)。
下面几种方法都可以帮你去除这些动画

//方法一
[UIView performWithoutAnimation:^{
[collectionView reloadItemsAtIndexPaths:@[[NSIndexPath indexPathForItem:index inSection:0]]];
}];
//方法二
[UIView animateWithDuration:0 animations:^{
[collectionView performBatchUpdates:^{
[collectionView reloadItemsAtIndexPaths:@[[NSIndexPath indexPathForItem:index inSection:0]]];
} completion:nil];
}];
//方法三
[UIView setAnimationsEnabled:NO];
[self.trackPanel performBatchUpdates:^{
[collectionView reloadItemsAtIndexPaths:@[[NSIndexPath indexPathForItem:index inSection:0]]];
} completion:^(BOOL finished) {
[UIView setAnimationsEnabled:YES];
}];

• 让Xcode的控制台支持LLDB类型的打印

打开终端输入三条命令:

touch ~/.lldbinit
echo display @import UIKit >> ~/.lldbinit
echo target stop-hook add -o \"target stop-hook disable\" >> ~/.lldbinit

• CocoaPods pod install/pod update更新慢的问题

pod install --verbose --no-repo-update
pod update --verbose --no-repo-update
如果不加后面的参数，默认会升级CocoaPods的spec仓库，加一个参数可以省略这一步，然后速度就会提升不少

• GCD timer定时器

dispatch_queue_t queue = dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0);
dispatch_source_t timer = dispatch_source_create(DISPATCH_SOURCE_TYPE_TIMER, 0, 0,queue);
dispatch_source_set_timer(timer,dispatch_walltime(NULL, 0),1.0*NSEC_PER_SEC, 0); //每秒执行
dispatch_source_set_event_handler(timer, ^{
    //@"倒计时结束，关闭"
    dispatch_source_cancel(timer);
    dispatch_async(dispatch_get_main_queue(), ^{
    });
});
dispatch_resume(timer);

• 禁用UIWebView的默认交互行为

public func webViewDidFinishLoad(webView: UIWebView) {
        if disableUserSelect { // 禁用用户选择
          webView.stringByEvaluatingJavaScriptFromString("document.documentElement.style.webkitUserSelect='none';")
        }
        if disableLongTouch { // 禁用长按弹出框
          webView.stringByEvaluatingJavaScriptFromString("document.documentElement.style.webkitTouchCallout='none';")
        }
}

• UIButton 移除所有事件

button.removeTarget(nil, action: nil, forControlEvents: .AllEvents)

• 在模拟器中添加视频

//Add a video in Simulator
if let a = NSBundle.mainBundle().pathForResource("test", ofType: "mov", inDirectory: nil) {
    UISaveVideoAtPathToSavedPhotosAlbum(a, self, nil, nil)
}

• 液晶时钟字体

label.font=[UIFont fontWithName:@"DBLCDTempBlack" size:60.0];

• UIAlertController改变按钮文字颜色

alertC.view.tintColor = your color;
//setting the tintColor after presenting the controller works on both iOS 8 and 9

• Getting an iPhone UDID from Mobile Safari

---

问题集锦

• Can't add self as subview

iOS7刚发布的时候，总是出现这个 Can't add self as subview 的崩溃，异常描述和崩溃堆栈是这样的：

Terminating app due to uncaught exception 'NSInvalidArgumentException', reason: 'Can't add self as subview' 

这是因为导航栏在做动画的时候，执行了一次[self addSubView:self]
为了防止这种情况，我们在UINavigationController基类中加入防御，具体做法是在push，pop方法中设置一个标志位(animating=YES)，在动画结束之后，再重置这个标志位，然后，用这个标志位判断push和pop操作是否能够执行。

@interface UIViewController (Animating)
@property (nonatomic, assign) BOOL animating;
@end

@implementation BaseNavigationController
-(void)pushViewController:(UIViewController *)viewController animated:(BOOL)animated
{
    if (topVC.animating) {
        return;
    }
    topVC.animating = YES;
    viewController.animating = YES;
    [super pushViewController:viewController animated:animated];
}
@end

@implementation BaseKitViewController
-(void)viewDidAppear:(BOOL)animated {
    [super viewDidAppear:animated];
    self.animating = NO;
}
-(void)viewDidDisappear:(BOOL)animated {
    [super viewDidDisappear:animated];
    self.animating = NO;
}
@end

• TestFlight上传不成功提示ITSAppUsesNonExemptEncryption

info.plist添加下面键值对

ITSAppUsesNonExemptEncryption

• Xcode8 手动创建桥接文件Bridge-Header

• Xib颜色设置有色差