效果如上所示。

主要的代码：

//
//  JieSuo.m
//  手势解锁
//
//  Created by 键盘上的舞者 on 15/8/17.
//  Copyright (c) 2015年 键盘上的舞者. All rights reserved.
//

#import "JieSuo.h"

@interface JieSuo()

@property(nonatomic,strong) NSMutableArray *btns;
@property(nonatomic,assign) CGPoint pointP;

@end

@implementation JieSuo

-(NSMutableArray *)btns
{
    if(_btns==nil)
    {
        _btns=[NSMutableArray array];
    }
    return _btns;
}

-(id)initWithCoder:(NSCoder *)aDecoder
{
    
    if(self=[super initWithCoder:aDecoder])
    {
        [self addBtns];
    }
    return self;
}

-(void)addBtns
{
    for(int i=0;i<9;i++){
        UIButton *btn=[UIButton buttonWithType:UIButtonTypeCustom];
        btn.tag=i+1;
        [btn setImage:[UIImage imageNamed:@"gesture_node_normal"] forState:UIControlStateNormal];
        [btn setImage:[UIImage imageNamed:@"gesture_node_highlighted"] forState:UIControlStateSelected];
        btn.userInteractionEnabled=NO;
        [self addSubview:btn];
    }
}

-(void)layoutSubviews
{
    [super layoutSubviews];
    CGFloat col=0;
    CGFloat row=0;
    CGFloat btnW=74;
    CGFloat btnH=74;
    CGFloat btnX=0;
    CGFloat btnY=0;
    CGFloat tolcol=3;
    CGFloat margin=(self.bounds.size.width -btnW*3)/(tolcol +1);
    for(int i=0;i<self.subviews.count;i++){
        UIButton *btn=self.subviews[i];
        
        col = i % 3;
        row = i / 3;
        btnX=margin+(margin+btnW)*col;
        btnY=(btnH+margin)*row;
        
        btn.frame=CGRectMake(btnX, btnY, btnW, btnH);
        
    }
    
}
//获取触摸点
-(CGPoint)pointWithTouches:(NSSet *)touches
{
    UITouch *touch=[touches anyObject];
    return [touch locationInView:self];
}
//获取触摸按钮
-(UIButton *)buttonWithPoint:(CGPoint)point
{
    for(UIButton *btn in self.subviews){
        if(CGRectContainsPoint(btn.frame, point)){
            return btn;
        }
    }
    return nil;
}

-(void)touchesBegan:(NSSet *)touches withEvent:(UIEvent *)event
{
    CGPoint pos=[self pointWithTouches:touches];
    UIButton *btn=[self buttonWithPoint:pos];
    if(btn&&btn.selected==NO){
        btn.selected=YES;
        [_btns addObject:btn];
    }
}

-(void)touchesMoved:(NSSet *)touches withEvent:(UIEvent *)event
{
    
    CGPoint pos=[self pointWithTouches:touches];
    _pointP=pos;
    UIButton *btn=[self buttonWithPoint:pos];
    if(btn && btn.selected==NO){
        btn.selected=YES;
        [_btns addObject:btn];
    }
    [self setNeedsDisplay];
}

-(void)touchesEnded:(NSSet *)touches withEvent:(UIEvent *)event
{
//    NSMutableString *str=[[NSMutableString alloc] init];
//    for (UIButton *btn in _btns) {
//        [str appendFormat:@"%d",btn.tag];
//    }
//    NSLog(@"密码是:%@",str);
    //退出的时候清楚所有手势
    [self.btns makeObjectsPerformSelector:@selector(setSelected:) withObject:@NO];
    [_btns removeAllObjects];
    [self setNeedsDisplay];
}

- (void)drawRect:(CGRect)rect {
    UIBezierPath *path=[UIBezierPath bezierPath];
    for (int i=0; i<self.btns.count; i++) {
        UIButton *btn=_btns[i];
        if(i==0){
            [path moveToPoint:btn.center];
        }else{
            [path addLineToPoint:btn.center];
        }
    }
    [path addLineToPoint:_pointP];
    path.lineWidth=8;
    path.lineJoinStyle=kCGLineJoinRound;
    [[UIColor greenColor] set];
    [path stroke];
}


@end