编码篇-iOS开发中的奇巧小伎

self.tableView.tableFooterView = [[UIView alloc] init];

NSString中需要格式化的字符串中百分号使用％％表示
例如：NSLog(@"%%%@%%",@"hello"),控制台会打印出％hello％。
自己键盘打出的 % 汉字形式下的还是会报警告，并且不会显示出来.把上文的粘贴过去使用吧！

[UIApplication sharedApplication].idleTimerDisabled = YES;

// 跳进app设置
if (UIApplicationOpenSettingsURLString != NULL) {
    NSURL *url = [NSURL URLWithString:UIApplicationOpenSettingsURLString];
    [[UIApplication sharedApplication] openURL:url];
}
测试注意：新项目测试，需要请求一下位置权限或者通知权限，才可以跳进自己的app设置里面（必须在info.plist 中设置私有属性的访问权限）
你的应用要提前至少申请了某一个权限，如（通知，定位等）。否则，会引起崩溃。

collectionView.alwaysBounceHorizontal = YES;
collectionView.alwaysBounceVertical = YES;

[self.navigationController.navigationBar setTitleTextAttributes:@{NSForegroundColorAttributeName : [UIColor youColor], NSFontAttributeName : [UIFont systemFontOfSize:15]}]

[[[UIApplication sharedApplication] keyWindow] endEditing:YES];

1、找到你想用的字体的 ttf 格式，拖入工程
2、在工程的plist中增加一行数组，“Fonts provided by application”
3、为这个key添加一个item，value为你刚才导入的ttf文件名
4、直接使用即可：label.font = [UIFont fontWithName:@"你刚才导入的ttf文件名" size:20.0]；

使用以下代码调用即可：
if (! obj) { return; }
SEL selector = NSSelectorFromString(@"aMethod");
IMP imp = [obj methodForSelector:selector];
void (*func)(id, SEL) = (void *)imp;
func(obj, selector);

或者：
SEL selector = NSSelectorFromString(@"aMethod");
((void (*)(id, SEL))[obj methodForSelector:selector])(obj, selector);

isKindOfClass  可以判断某个对象是否属于某个类，或者这个类的子类。
isMemberOfClass  更加精准，它只能判断这个对象是否是某一个类的实例(不能判断子类)

label.font.pointSize

// 左上角和右下角添加圆角
UIBezierPath *maskPath = [UIBezierPath bezierPathWithRoundedRect:view.bounds byRoundingCorners:(UIRectCornerTopLeft | UIRectCornerBottomRight) cornerRadii:CGSizeMake(20, 20)];
CAShapeLayer *maskLayer = [CAShapeLayer layer];
maskLayer.frame = view.bounds;
maskLayer.path = maskPath.CGPath;
view.layer.mask = maskLayer;

最上面
[parentView bringSubviewToFront:yourView]
最下面
[parentView sendSubviewToBack:yourView]

需要导入框架  
#import <AudioToolbox/AudioToolbox.h>
AudioServicesPlayAlertSound(kSystemSoundID_Vibrate);

1、打开摇一摇功能
[UIApplication sharedApplication].applicationSupportsShakeToEdit = YES;
2、让需要摇动的控制器成为第一响应者
[self becomeFirstResponder];
3、实现以下方法

// 开始摇动
- (void)motionBegan:(UIEventSubtype)motion withEvent:(UIEvent *)event
// 取消摇动
- (void)motionCancelled:(UIEventSubtype)motion withEvent:(UIEvent *)event
// 摇动结束
- (void)motionEnded:(UIEventSubtype)motion withEvent:(UIEvent *)event

[segment setTitleTextAttributes:@{NSFontAttributeName : [UIFont systemFontOfSize:15.0f]} forState:UIControlStateNormal];

// view分类方法
- (UIViewController *)belongViewController {
    for (UIView *next = [self superview]; next; next = next.superview) {
        UIResponder* nextResponder = [next nextResponder];
        if ([nextResponder isKindOfClass:[UIViewController class]]) {
          return (UIViewController *)nextResponder;
       }
    }
  return nil;
}

 // view分类方法
- (NSString *)encodeToBase64String:(UIImage *)image {
 return [UIImagePNGRepresentation(image) base64EncodedStringWithOptions:NSDataBase64Encoding64CharacterLineLength];
}

- (UIImage *)decodeBase64ToImage:(NSString *)strEncodeData {
  NSData *data = [[NSData alloc]initWithBase64EncodedString:strEncodeData options:NSDataBase64DecodingIgnoreUnknownCharacters];
  return [UIImage imageWithData:data];
}

// point是否在rect内
BOOL isContains = CGRectContainsPoint(rect, point);

// 继承UITextView重写这个方法
- (BOOL)canPerformAction:(SEL)action withSender:(id)sender
{
// 返回NO为禁用，YES为开启
    // 粘贴
    if (action == @selector(paste:)) return NO;
    // 剪切
    if (action == @selector(cut:)) return NO;
    // 复制
    if (action == @selector(copy:)) return NO;
    // 选择
    if (action == @selector(select:)) return NO;
    // 选中全部
    if (action == @selector(selectAll:)) return NO;
    // 删除
    if (action == @selector(delete:)) return NO;
    // 分享
    if (action == @selector(share)) return NO;
    return [super canPerformAction:action withSender:sender];
}

// 方法一、
// 把参数放进一个数组／字典，直接把数组／字典当成一个参数传过去，具体方法实现的地方再解析这个数组／字典
NSArray * array =  [NSArray arrayWithObjects: @"first", @"second", nil];
[self performSelector:@selector(fooFirstInput:) withObject: array afterDelay:15.0];

// 方法二、
// 使用NSInvocation
SEL aSelector = NSSelectorFromString(@"doSoming:argument2:");
    NSInteger argument1 = 10;
    NSString *argument2 = @"argument2";
    if([self respondsToSelector:aSelector]) {
          NSInvocation *inv = [NSInvocation invocationWithMethodSignature:[self methodSignatureForSelector:aSelector]];
        [inv setSelector:aSelector];
        [inv setTarget:self];
        [inv setArgument:&(argument1) atIndex:2];
        [inv setArgument:&(argument2) atIndex:3];
        [inv performSelector:@selector(invoke) withObject:nil afterDelay:15.0];
    }

if (CGRectEqualToRect(rect1, rect2)) { // 两个区域相等
    // do some
}
if (CGPointEqualToPoint(point1, point2)) { // 两个点相等
    // do some
}
if (CGSizeEqualToSize(size1, size2)) { // 两个size相等
    // do some
}

 NSDate* date1 = someDate;
 NSDate* date2 = someOtherDate;
 NSTimeInterval distanceBetweenDates = [date1 timeIntervalSinceDate:date2];
 double secondsInAnHour = 3600;
// 除以3600是把秒化成小时，除以60得到结果为相差的分钟数
 NSInteger hoursBetweenDates = distanceBetweenDates / secondsInAnHour;

// 加入现在有三张图片分别为animate_1、animate_2、animate_3
// 方法一
  imageView.animationImages = @[[UIImage imageNamed:@"animate_1"], [UIImage imageNamed:@"animate_2"], [UIImage imageNamed:@"animate_3"]];
  imageView.animationDuration = 1.0;
// 方法二
  imageView.image = [UIImage animatedImageNamed:@"animate_" duration:1.0];
// 方法二解释下，这个方法会加载animate_为前缀的，后边0-1024，也就是animate_0、animate_1一直到a

 if (CGRectIntersectsRect(rect1, rect2)) {
}

NSCharacterSet *notDigits = [[NSCharacterSet decimalDigitCharacterSet] invertedSet];
if ([str rangeOfCharacterFromSet:notDigits].location == NSNotFound)
{   // 是数字
} else{
  // 不是数字
 }

- (void)createPDFfromUIView:(UIView*)aView saveToDocumentsWithFileName:(NSString*)aFilename
  {
      NSMutableData *pdfData = [NSMutableData data];
      UIGraphicsBeginPDFContextToData(pdfData, aView.bounds, nil);
      UIGraphicsBeginPDFPage();
      CGContextRef pdfContext = UIGraphicsGetCurrentContext();
      [aView.layer renderInContext:pdfContext];
      UIGraphicsEndPDFContext();

    NSArray* documentDirectories = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask,YES);
    NSString* documentDirectory = [documentDirectories objectAtIndex:0];
    NSString* documentDirectoryFilename = [documentDirectory stringByAppendingPathComponent:aFilename];
    [pdfData writeToFile:documentDirectoryFilename atomically:YES];
    NSLog(@"documentDirectoryFileName: %@",documentDirectoryFilename);
}

- (UIViewController *)backViewController
{
    NSInteger myIndex = [self.navigationController.viewControllers indexOfObject:self];
    if ( myIndex != 0 && myIndex != NSNotFound ) {
        return [self.navigationController.viewControllers objectAtIndex:myIndex-1];
    } else {
        return nil;
    }
  }

  NSArray *paths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES);
  NSString *filePath = [[paths objectAtIndex:0] stringByAppendingPathComponent:@"Image.png"];

  [UIImagePNGRepresentation(image) writeToFile:filePath atomically:YES];

// 方法一
CATransition *animation = [CATransition animation];
animation.timingFunction = [CAMediaTimingFunction functionWithName:kCAMediaTimingFunctionEaseInEaseOut];
animation.type = kCATransitionFade;
animation.duration = 0.75;
[self.label.layer addAnimation:animation forKey:@"kCATransitionFade"];
self.label.text = @"New";

// 方法二
[UIView transitionWithView:self.label
                  duration:0.25f
                   options:UIViewAnimationOptionTransitionCrossDissolve
                animations:^{
                    self.label.text = @"Well done!";
                } completion:nil];

// 方法三
[UIView animateWithDuration:1.0
                 animations:^{
                     self.label.alpha = 0.0f;
                     self.label.text = @"newText";
                     self.label.alpha = 1.0f;
                 }];

// 如果myView是self.view本身，也会返回yes,
BOOL isSubView = [myView isDescendantOfView:self.view];

// 需要导入#import
mach_port_t host_port;
mach_msg_type_number_t host_size;
vm_size_t pagesize;

host_port = mach_host_self();
host_size = sizeof(vm_statistics_data_t) / sizeof(integer_t);
host_page_size(host_port, &pagesize);

vm_statistics_data_t vm_stat;

if (host_statistics(host_port, HOST_VM_INFO, (host_info_t)&vm_stat, &host_size) != KERN_SUCCESS) {
    NSLog(@"Failed to fetch vm statistics");
}

/* Stats in bytes */
natural_t mem_used = (vm_stat.active_count +
                      vm_stat.inactive_count +
                      vm_stat.wire_count) * pagesize;
natural_t mem_free = vm_stat.free_count * pagesize;
natural_t mem_total = mem_used + mem_free;
NSLog(@"已用: %u 可用: %u 总共: %u", mem_used, mem_free, mem_total);

UITextView *textView = [[UITextView alloc] initWithFrame:CGRectMake(20, 30, 100, 199)];
textView.backgroundColor = [UIColor redColor];
[self.view addSubview:textView];
NSString *htmlString = @"";
NSAttributedString *attributedString = [[NSAttributedString alloc] initWithData: [htmlString dataUsingEncoding:NSUnicodeStringEncoding] options: @{ NSDocumentTypeDocumentAttribute: NSHTMLTextDocumentType } documentAttributes: nil error: nil];
textView.attributedText = attributedString;

[self.textView setSelectedTextRange:[self.textView textRangeFromPosition:self.textView.beginningOfDocument toPosition:self.textView.endOfDocument]]

textField.tintColor = [UIColor clearColor];

textField.enablesReturnKeyAutomatically = YES;

UIApplicationDidEnterBackgroundNotification 应用程序进入后台
UIApplicationWillEnterForegroundNotification 应用程序将要进入前台
UIApplicationDidFinishLaunchingNotification 应用程序完成启动
UIApplicationDidFinishLaunchingNotification 应用程序由挂起变的活跃
UIApplicationWillResignActiveNotification 应用程序挂起(有电话进来或者锁屏)
UIApplicationDidReceiveMemoryWarningNotification 应用程序收到内存警告
UIApplicationDidReceiveMemoryWarningNotification 应用程序终止(后台杀死、手机关机等)
UIApplicationSignificantTimeChangeNotification 当有重大时间改变(凌晨0点，设备时间被修改，时区改变等)
UIApplicationWillChangeStatusBarOrientationNotification 设备方向将要改变
UIApplicationDidChangeStatusBarOrientationNotification 设备方向改变
UIApplicationWillChangeStatusBarFrameNotification 设备状态栏frame将要改变
UIApplicationDidChangeStatusBarFrameNotification 设备状态栏frame改变
UIApplicationBackgroundRefreshStatusDidChangeNotification 应用程序在后台下载内容的状态发生变化
UIApplicationProtectedDataWillBecomeUnavailable 本地受保护的文件被锁定,无法访问
UIApplicationProtectedDataWillBecomeUnavailable 本地受保护的文件可用了

UICollectionViewLayoutAttributes *attributes = [collectionView layoutAttributesForItemAtIndexPath:indexPath];
CGRect cellRect = attributes.frame;
CGRect cellFrameInSuperview = [collectionView convertRect:cellRect toView:[cv superview]];

// 子类化UITextField，增加insert属性
@interface WZBTextField : UITextField
@property (nonatomic, assign) UIEdgeInsets insets;
@end

// 在.m文件重写下列方法
- (CGRect)textRectForBounds:(CGRect)bounds {
CGRect paddedRect = UIEdgeInsetsInsetRect(bounds, self.insets);
if (self.rightViewMode == UITextFieldViewModeAlways || self.rightViewMode == UITextFieldViewModeUnlessEditing) {
    return [self adjustRectWithWidthRightView:paddedRect];
}
return paddedRect;
}

- (CGRect)placeholderRectForBounds:(CGRect)bounds {
CGRect paddedRect = UIEdgeInsetsInsetRect(bounds, self.insets);

if (self.rightViewMode == UITextFieldViewModeAlways || self.rightViewMode == UITextFieldViewModeUnlessEditing) {
    return [self adjustRectWithWidthRightView:paddedRect];
}
return paddedRect;
}

 - (CGRect)editingRectForBounds:(CGRect)bounds {
CGRect paddedRect = UIEdgeInsetsInsetRect(bounds, self.insets);
if (self.rightViewMode == UITextFieldViewModeAlways || self.rightViewMode == UITextFieldViewModeWhileEditing) {
    return [self adjustRectWithWidthRightView:paddedRect];
}
return paddedRect;
}

- (CGRect)adjustRectWithWidthRightView:(CGRect)bounds {
    CGRect paddedRect = bounds;
    paddedRect.size.width -= CGRectGetWidth(self.rightView.frame);

    return paddedRect;
}

- (BOOL)image:(UIImage *)image1 isEqualTo:(UIImage *)image2
{
      NSData *data1 = UIImagePNGRepresentation(image1);
      NSData *data2 = UIImagePNGRepresentation(image2);

      return [data1 isEqual:data2];
}

// brightness属性值在0-1之间，0代表最小亮度，1代表最大亮度
[[UIScreen mainScreen] setBrightness:0.5];

CGFloat f = 4.65;
NSLog(@"%d", (int)f);    // 打印结果4

CGFloat f = 4.65;
NSLog(@"%d", (int)round(f));    // 打印结果5

[scrollView setContentOffset:scrollView.contentOffset animated:NO];

// 假设你的自定义view名字为CustomView，你需要在CustomView.m中重写 `- (instancetype)initWithCoder:(NSCoder *)aDecoder` 方法，代码如下：
- (instancetype)initWithCoder:(NSCoder *)aDecoder {
if ((self = [super initWithCoder:aDecoder])) {
    [self addSubview:[[[NSBundle mainBundle] loadNibNamed:@"CustomView" owner:self options:nil] objectAtIndex:0]];
}
return self;
}

NSString *str = @"abcdefghijklmn";
NSString *resultStr;
if (str && str.length > 0) {
    resultStr = [str stringByReplacingCharactersInRange:NSMakeRange(0,1) withString:[[str substringToIndex:1] capitalizedString]];
}
NSLog(@"%@", resultStr);

- (NSString *)getNumberFromStr:(NSString *)str
{
    NSCharacterSet *nonDigitCharacterSet = [[NSCharacterSet decimalDigitCharacterSet] invertedSet];
    return [[str componentsSeparatedByCharactersInSet:nonDigitCharacterSet] componentsJoinedByString:@""];
}

  NSLog(@"%@", [self getNumberFromStr:@"a0b0c1d2e3f4fda8fa8fad9fsad23"]); // 00123488923

// 输入框文字改变的时候调用
-(void)searchBar:(UISearchBar *)searchBar textDidChange:(NSString *)searchText{
    // 先取消调用搜索方法
    [NSObject cancelPreviousPerformRequestsWithTarget:self selector:@selector(searchNewResult) object:nil];
    // 0.5秒后调用搜索方法
    [self performSelector:@selector(searchNewResult) withObject:nil afterDelay:0.5];
}

// UIView有个属性叫做exclusiveTouch，设置为YES后，其响应事件会和其他view互斥(有其他view事件响应的时候点击它不起作用)
view.exclusiveTouch = YES;

// 一个一个设置太麻烦了，可以全局设置
[[UIView appearance] setExclusiveTouch:YES];

// 或者只设置button
[[UIButton appearance] setExclusiveTouch:YES];

// 子类化UITabBarViewController，我这里以修改tabBar高度为例，重写viewWillLayoutSubviews方法
#import "WZBTabBarViewController.h"

@interface WZBTabBarViewController ()

@end

@implementation WZBTabBarViewController
- (void)viewWillLayoutSubviews {

    CGRect tabFrame = self.tabBar.frame;
    tabFrame.size.height = 100;
    tabFrame.origin.y = self.view.frame.size.height - 100;
    self.tabBar.frame = tabFrame;
}
@end

// 设置某个键盘颜色
textField.keyboardAppearance = UIKeyboardAppearanceAlert;

// 设置工程中所有键盘颜色
[[UITextField appearance] setKeyboardAppearance:UIKeyboardAppearanceAlert];

- (void)navigationController:(UINavigationController *)navigationController willShowViewController:(UIViewController *)viewController animated:(BOOL)animated
{
    [[UIApplication sharedApplication] setStatusBarStyle:UIStatusBarStyleLightContent];
}

 [self.navigationController.navigationBar setBackgroundImage:[UIImage new]
                         forBarMetrics:UIBarMetricsDefault];
self.navigationController.navigationBar.shadowImage = [UIImage new];
self.navigationController.navigationBar.translucent = YES;