iOS实现拖拽View跟随手指浮动效果

//
// OrangeView.m
// 拖拽View跟随手指浮动
//
// Created by llkj on 2017/8/16.
// Copyright © 2017年 LayneCheung. All rights reserved.
//

#import "OrangeView.h"

@implementation OrangeView

//当开始触摸屏幕的时候调用
- (void)touchesBegan:(NSSet *)touches withEvent:(UIEvent *)event{

 NSLog(@"%s", __func__);
}

//触摸时开始移动时调用(移动时会持续调用)
//NSSet:无序
//NSArray:有序
- (void)touchesMoved:(NSSet *)touches withEvent:(UIEvent *)event{

 NSLog(@"%s", __func__);

 UITouch *touch = [touches anyObject];

 //求偏移量 = 手指当前点的X - 手指上一个点的X
 CGPoint currentPoint = [touch locationInView:self];
 CGPoint prePoint = [touch previousLocationInView:self];

 NSLog(@"ccurrentPoint = %@", NSStringFromCGPoint(currentPoint));
 NSLog(@"prePiont = %@", NSStringFromCGPoint(prePoint));

 CGFloat offSetX = currentPoint.x - prePoint.x;
 CGFloat offSetY = currentPoint.y - prePoint.y;

 //平移
 self.transform = CGAffineTransformTranslate(self.transform, offSetX, offSetY);
}

//当手指离开屏幕时调用
-(void)touchesEnded:(NSSet *)touches withEvent:(UIEvent *)event{

 NSLog(@"%s", __func__);
}

//当发生系统事件时就会调用该方法(电话打入,自动关机)
- (void)touchesCancelled:(NSSet *)touches withEvent:(UIEvent *)event{

 NSLog(@"%s", __func__);
}
@end