Person *p = [Person new];// 调用对象p的test方法[p performSelector:@selector(test)];[person performSelector:@selector(test2:) withObject:@"传入参数"];

Person类代码：#import "Person.h"@implementation Person- (void)test{    NSLog(@"无参数的对象方法");}- (void)test2:(NSString *)str{    NSLog(@"带有参数的方法%@",str);}@end

// 对一个数组array的每个元素执行一次test方法[array makeObjectsPerformSelector:@selector(test)];[array makeObjectsPerformSelector:@selector(test)  withObject:@"aaa"];//对一个数组array进行排序[array sortedArrayUsingSelector:@selector(compare:)];

#import <UIKit/UIKit.h>@interface TapView : UIView//目标@property(weak,nonatomic)id target;//行为@property(assign,nonatomic)SEL action;//自定义方法-(void)addCustomtarget:(id)target andAction:(SEL)action;@end

#import "TapView.h"@implementation TapView//自定义方法-(void)addCustomtarget:(id)target andAction:(SEL)action{    _action = action;    _target = target;}-(void)touchesBegan:(NSSet<UITouch *> *)touches withEvent:(UIEvent *)event{    //当视图点击的时候,target去执行action的方法并把自己传过去.    //首先代理不能是空,而且代理(代理是对象!)的类中有方法并且能传出过来.    if (nil != _target && [[_target class] instancesRespondToSelector:_action]) {        [_target performSelector:_action withObject:self];    }}

#import <Foundation/Foundation.h>#import <objc/runtime.h>#import "Debug.h" // not given; just an assert@interface NSObject (Extras)// Enforce the rule that the selector used must return void.- (void) performVoidReturnSelector:(SEL)aSelector withObject:(id)object;- (void) performVoidReturnSelector:(SEL)aSelector;@end@implementation NSObject (Extras)// Apparently the reason the regular performSelect gives a compile time warning is that the system doesn‘t know the return type. I‘m going to (a) make sure that the return type is void, and (b) disable this warning// See http://stackoverflow.com/questions/7017281/performselector-may-cause-a-leak-because-its-selector-is-unknown- (void) checkSelector:(SEL)aSelector {    // See http://stackoverflow.com/questions/14602854/objective-c-is-there-a-way-to-check-a-selector-return-value    Method m = class_getInstanceMethod([self class], aSelector);    char type[128];    method_getReturnType(m, type, sizeof(type));    NSString *message = [[NSString alloc] initWithFormat:@"NSObject+Extras.performVoidReturnSelector: %@.%@ selector (type: %s)", [self class], NSStringFromSelector(aSelector), type];    NSLog(@"%@", message);    if (type[0] != ‘v‘) {        message = [[NSString alloc] initWithFormat:@"%@ was not void", message];        [Debug assertTrue:FALSE withMessage:message];    }}- (void) performVoidReturnSelector:(SEL)aSelector withObject:(id)object {    [self checkSelector:aSelector];#pragma clang diagnostic push#pragma clang diagnostic ignored "-Warc-performSelector-leaks"    // Since the selector (aSelector) is returning void, it doesn‘t make sense to try to obtain the return result of performSelector. In fact, if we do, it crashes the app.    [self performSelector: aSelector withObject: object];#pragma clang diagnostic pop    }- (void) performVoidReturnSelector:(SEL)aSelector {    [self checkSelector:aSelector];#pragma clang diagnostic push#pragma clang diagnostic ignored "-Warc-performSelector-leaks"    [self performSelector: aSelector];#pragma clang diagnostic pop}@end

#import <UIKit/UIKit.h>@protocol TouchViewDelegate <NSObject>-(void)changeViewColor:(UIColor *)color;@end@interface TouchView : UIView//声明一个代理,这个代理遵守TouchViewDelegate协议,@property(nonatomic,assign)id<TouchViewDelegate> delegate;@end

#import "TouchView.h"@implementation TouchView//我们还是用touchesBegandian-(void)touchesBegan:(NSSet<UITouch *> *)touches withEvent:(UIEvent *)event{    if (nil != self.delegate && [self.delegate respondsToSelector:@selector(changeViewColor:)]) {        //我们传一个颜色到我们的ViewController去.        [self.delegate changeViewColor:[UIColor brownColor]];    }}@end

运用代码：#import "ViewController.h"#import "TouchView.h"//在这里ViewController 要遵守协议....@interface ViewController ()<TouchViewDelegate>@property(nonatomic,strong)TouchView *touchView;@end@implementation ViewController- (void)viewDidLoad {    [super viewDidLoad];    self.touchView = [[TouchView alloc]initWithFrame:CGRectMake(100, 100, 100, 100)];    self.touchView.backgroundColor = [UIColor redColor];    //指定touchView的代理为ViewController.即为本身~    self.touchView.delegate =self;    [self.view addSubview: self.touchView];}-(void)changeViewColor:(UIColor *)color{    //现在参数color是有值的,这是因为在TouchView那个页面传过来的.    self.touchView.backgroundColor = color;}@end

#import <UIKit/UIKit.h>//给block改名成MyBlocktypedef void(^MyBlock)(NSString *);@interface OtherViewController : UIViewController//ARC:语义设置使用strong即可@property(nonatomic,strong)MyBlock block;@end

#import "OtherViewController.h"@interface OtherViewController ()@property(nonatomic,strong)UITextField *textField;@end@implementation OtherViewController- (void)viewDidLoad {    [super viewDidLoad];    self.textField = [[UITextField alloc]initWithFrame:CGRectMake(0, 100, 414, 40)];    self.textField.backgroundColor = [UIColor lightGrayColor];    self.view.backgroundColor = [UIColor whiteColor];    [self.view addSubview: self.textField];}-(void)touchesBegan:(NSSet<UITouch *> *)touches withEvent:(UIEvent *)event{    self.block(_textField.text);    [self.navigationController popViewControllerAnimated:YES];}@end

运用代码：    OtherViewController *otherVC = [[OtherViewController alloc]init];    __weak typeof(self)weak = self;    //给block赋值~    otherVC.block = ^(NSString *string){        weak.label.text = string;    };    [self.navigationController pushViewController:otherVC animated:YES];

#pragma clang diagnostic push    #pragma clang diagnostic ignored "-Wdeprecated-declarations"      //会报警告的方法，比如SEL [TestFlight setDeviceIdentifier:[[UIDevice currentDevice] uniqueIdentifier]];    #pragma clang diagnostic pop  

#pragma clang diagnostic push   #pragma clang diagnostic ignored "-Wunused-variable"       int a;   #pragma clang diagnostic pop 

#import <UIKit/UIKit.h>//六边形Button@interface HexagonButton : UIViewNS_ASSUME_NONNULL_BEGINtypedef void (^HexagonButtonBlock)();@property (nonatomic, strong) UIBezierPath *path;@property (nonatomic, strong) CAShapeLayer *maskLayer;@property (nonatomic, strong) HexagonButtonBlock block; //点击事件//添加点击事件NS_ASSUME_NONNULL_END@end

#import "HexagonButton.h"@implementation HexagonButton- (instancetype) initWithFrame:(CGRect)frame{    if ([super initWithFrame:frame]) {                self.backgroundColor = [UIColor brownColor];        self.userInteractionEnabled = YES;                //添加单击手势        UITapGestureRecognizer * tap = [[UITapGestureRecognizer alloc] initWithTarget:self action:@selector(click:)];        [self addGestureRecognizer:tap];    }    return self;}- (void) layoutSubviews{    [super layoutSubviews];    CGFloat SIZE = self.frame.size.width;    // step 1: 生成六边形路径    CGFloat longSide = SIZE * 0.5 * cosf(M_PI * 30 / 180);    CGFloat shortSide = SIZE * 0.5 * sin(M_PI * 30 / 180);    CGFloat k = SIZE * 0.5 - longSide;  //路径整体下移，保证六边形路径位于图形中间        _path = [UIBezierPath bezierPath];    [_path moveToPoint:CGPointMake(0, longSide  + k)];    [_path addLineToPoint:CGPointMake(shortSide, + k)];    [_path addLineToPoint:CGPointMake(shortSide + shortSide + shortSide,  k)];    [_path addLineToPoint:CGPointMake(SIZE, longSide + k)];    [_path addLineToPoint:CGPointMake(shortSide * 3, longSide * 2 + k)];    [_path addLineToPoint:CGPointMake(shortSide, longSide * 2 + k)];    [_path closePath];        // step 2: 根据路径生成蒙板    _maskLayer = [CAShapeLayer layer];    //    _maskLayer.position = self.center;    _maskLayer.path = [_path CGPath];        // step 3: 添加蒙版    self.layer.mask = _maskLayer;    self.backgroundColor = [UIColor orangeColor];}//点击事件- (void) click:(UITapGestureRecognizer *) tap{    if (_block) {        _block();    }}- (UIView *)hitTest:(CGPoint)point withEvent:(UIEvent *)event {    //如果点击的区域在所创建的路径范围内    if (CGPathContainsPoint(_path.CGPath, NULL, point, NO)) {        return [super hitTest:point withEvent:event];    }    return nil;}@end

    //创建六变形按钮    HexagonButton * hexagonButton = [[HexagonButton alloc] initWithFrame:CGRectMake(20, 20, 100, 100)];    hexagonButton.center = self.view.center;    hexagonButton.block = ^(){        NSLog(@"六边形区域被点击");    };    [self.view addSubview:hexagonButton];

var controllerArr = self.navigationController?.viewControllers//获取Controller数组controllerArr?.removeAll()//移除controllerArr中保存的历史路径    //重新添加新的路径controllerArr?.append(self.navigationController?.viewControllers[0])controllerArr?.append(C)controllerArr?.append(B)    //这时历史路径为（root -> c -> b）    //将组建好的新的跳转路径 set进self.navigationController里self.navigationController?.setViewControllers(controllerArr!, animated: true)//直接写入，完成跳转B页面的同时修改了之前的跳转路径