iOS开发基础知识--碎片45
Posted 李洪强
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ios开发基础知识--碎片45
1:iOS SEL的简单总结
SEL就是对方法的一种包装。包装的SEL类型数据它对应相应的方法地址,找到方法地址就可以调用方法
a.方法的存储位置
在内存中每个类的方法都存储在类对象中
每个方法都有一个与之对应的SEL类型的数据
根据一个SEL数据就可以找到对应的方法地址,进而调用方法
SEL类型的定义: typedef struct objc_selector *SEL
b.SEL对象的创建
SEL s1 = @selector(test1); // 将test1方法包装成SEL对象
SEL s2 = NSSelectorFromString(@"test1"); // 将一个字符串方法转换成为SEL对象
c.SEL对象的其他用法
// 将SEL对象转换为NSString对象
NSString *str = NSStringFromSelector(@selector(test));
实例:
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
d:在数组中的运用
// 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:)];
e:关于Sel传参运用(target - action设计模式)
在Button中我们经常用下面进行事件增加代码:
- (void)addTarget:(nullable id)target action:(SEL)action forControlEvents:(UIControlEvents)controlEvents;
实例:
#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]; } }
另一个实例:
#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
2:代理模式实例
#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
3:关于Bolck运用
#import <UIKit/UIKit.h> //给block改名成MyBlock typedef 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];
4:UIButton的几种触发方式
a、UIControlEventTouchDown
指鼠标左键按下(注:只是“按下”)的动作
b、UIControlEventTouchDownRepeat
指鼠标左键连续多次重复按下(注:只是“按下”)的动作,比如,鼠标连续双击、三击、……、多次连击。
说明:多次重复按下时,事件序列是这样的:
UIControlEventTouchDown ->
(UIControlEventTouchUpInside) ->
UIControlEventTouchDown ->
UIControlEventTouchDownRepeat ->
(UIControlEventTouchUpInside) ->
UIControlEventTouchDown ->
UIControlEventTouchDownRepeat ->
(UIControlEventTouchUpInside) ->
......
除了第一次按下外,后面每次摁下都是一个UIControlEventTouchDown事件,然后紧跟一个UIControlEventTouchDownRepeat事件。
c、UIControlEventTouchDragInside
指按下鼠标,然后在控件边界范围内拖动。
d、UIControlEventTouchDragOutside
与UIControlEventTouchDragInside不同的是,拖动时,鼠标位于控件边界范围之外。
但首先得有个UIControlEventTouchDown事件,然后接一个UIControlEventTouchDragInside事件,再接一个UIControlEventTouchDragExit事件,这时,鼠标已经位于控件外了,继续拖动就是UIControlEventTouchDragOutside事件了。
具体操作是:在控件里面按下鼠标,然后拖动到控件之外。
e、UIControlEventTouchDragEnter
指拖动动作中,从控件边界外到内时产生的事件。
f、UIControlEventTouchDragExit
指拖动动作中,从控件边界内到外时产生的事件。
g、UIControlEventTouchUpInside
指鼠标在控件范围内抬起,前提先得按下,即UIControlEventTouchDown或UIControlEventTouchDownRepeat事件。
h、UIControlEventTouchUpOutside
指鼠标在控件边界范围外抬起,前提先得按下,然后拖动到控件外,即
UIControlEventTouchDown ->
UIControlEventTouchDragInside(n 个) ->
UIControlEventTouchDragExit ->
UIControlEventTouchDragOutside(n 个)
时间序列,再然后就是抬起鼠标,产生UIControlEventTouchUpOutside事件。
5:让编译器对一些警告闭嘴
a:方法弃用告警
#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
b:未使用变量
#pragma clang diagnostic push #pragma clang diagnostic ignored "-Wunused-variable" int a; #pragma clang diagnostic pop
6:一个六边形,并只在六边形里面有点击效果
#import <UIKit/UIKit.h> //六边形Button @interface HexagonButton : UIView NS_ASSUME_NONNULL_BEGIN typedef 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];
7:self.navigationController.viewControllers修改
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
主要解决那些乱七八糟的转转,不按顺序来的问题;
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