iOS实现带有缩放效果的自动轮播图

#import <uikit/uikit.h> 
 
@interface customscrollview : uiview 
@property (strong,nonatomic) nsarray *imagearr; 
 
@end 

#import "customscrollview.h" 
 
@interface customscrollview ()<uiscrollviewdelegate> 
 
@property (strong,nonatomic) uiscrollview *scrollview; 
@property (strong,nonatomic) uiimageview *backimageview; 
 
@property (strong,nonatomic) uiimageview *leftiamgeview; 
@property (strong,nonatomic) uiimageview *middleimageview; 
@property (strong,nonatomic) uiimageview *rightimageview; 
 
@property (strong,nonatomic) uipagecontrol *pagecontrol; 
 
//高度 
@property (assign,nonatomic) cgfloat scrollviewheight; 
 
//手动造成的偏移量 
@property (assign,nonatomic) cgfloat offsetx; 
 
@property (strong,nonatomic) nstimer *timer; 
 
//属于计时器方法动画持续时间 ？ 
@property (assign,nonatomic) bool timeranimation; 
 
@end 
 
//左右内容的最大偏移量 
#define offset_max   ([uiscreen mainscreen].bounds.size.width-64)*0.9 
 
 
@implementation customscrollview 
 
- (instancetype)initwithframe:(cgrect)frame { 
 if (self = [super initwithframe:frame]) { 
 
  self.scrollviewheight = frame.size.height; 
   
  [self addsubview:self.backimageview]; 
  [self addsubview:self.scrollview]; 
  [self addsubview:self.pagecontrol]; 
   
  [self.backimageview mas_makeconstraints:^(masconstraintmaker *make) { 
   make.edges.with.mas_equalto(self); 
  }]; 
  [self.scrollview mas_makeconstraints:^(masconstraintmaker *make) { 
   make.edges.with.mas_equalto(self); 
  }]; 
  [self.pagecontrol mas_makeconstraints:^(masconstraintmaker *make) { 
   make.left.right.bottom.mas_equalto(self); 
   make.height.mas_equalto(@20); 
  }]; 
   
  self.timer = [nstimer scheduledtimerwithtimeinterval:5 target:self selector:@selector(timeraction) userinfo:nil repeats:yes]; 
  [[nsrunloop mainrunloop] addtimer:self.timer formode:nsdefaultrunloopmode]; 
  [self.timer setfiredate:[nsdate datewithtimeintervalsincenow:5]]; 
 } 
 return self; 
} 
 
- (nsarray *)imagearr { 
 if (!_imagearr) { 
  _imagearr = @[@"timg-0",@"timg-1",@"timg-2"]; 
 } 
 return _imagearr; 
} 
 
- (uiimageview *)backimageview { 
 if (!_backimageview) { 
  _backimageview = [[uiimageview alloc] init]; 
  _backimageview.image = [uiimage imagenamed:@"bg_home"]; 
 } 
 return _backimageview; 
} 
 
- (uiscrollview *)scrollview { 
 if (!_scrollview) { 
  _scrollview = [[uiscrollview alloc] init]; 
  _scrollview.showsverticalscrollindicator = no; 
  _scrollview.showshorizontalscrollindicator = no; 
  _scrollview.contentsize = cgsizemake(kscreenwidth+2*offset_max, self.scrollviewheight); 
  [_scrollview setcontentoffset:cgpointmake(offset_max, 0)]; 
  _scrollview.bounces = no; 
  _scrollview.delegate = self; 
   
  _leftiamgeview = [[uiimageview alloc] init]; 
  _leftiamgeview.image = [uiimage imagenamed:self.imagearr[0]]; 
  _leftiamgeview.layer.cornerradius = 5; 
  _leftiamgeview.layer.maskstobounds = yes; 
 
   
  _middleimageview = [[uiimageview alloc] init]; 
  _middleimageview.image = [uiimage imagenamed:self.imagearr[1]]; 
  _middleimageview.layer.cornerradius = 5; 
  _middleimageview.layer.maskstobounds = yes; 
 
   
  _rightimageview = [[uiimageview alloc] init]; 
  _rightimageview.image = [uiimage imagenamed:self.imagearr[2]]; 
  _rightimageview.layer.cornerradius = 5; 
  _rightimageview.layer.maskstobounds = yes; 
   
   
  [_scrollview addsubview:_leftiamgeview]; 
  [_scrollview addsubview:_middleimageview]; 
  [_scrollview addsubview:_rightimageview]; 
  [_leftiamgeview mas_makeconstraints:^(masconstraintmaker *make) { 
   make.size.mas_equalto(cgsizemake((kscreenwidth-64)*0.9, self.scrollviewheight*0.9)); 
   make.centery.mas_equalto(_scrollview); 
   make.right.mas_equalto(_middleimageview.mas_left).offset(-20); 
  }]; 
  [_middleimageview mas_makeconstraints:^(masconstraintmaker *make) { 
   make.size.mas_equalto(cgsizemake(kscreenwidth-64, self.scrollviewheight)); 
   make.centery.mas_equalto(_scrollview); 
   make.left.mas_equalto(_scrollview).offset(offset_max+64/2); 
  }]; 
  [_rightimageview mas_makeconstraints:^(masconstraintmaker *make) { 
   make.size.mas_equalto(_leftiamgeview); 
   make.centery.mas_equalto(_scrollview); 
   make.left.mas_equalto(_middleimageview.mas_right).offset(20); 
  }]; 
 } 
 return _scrollview; 
} 
 
- (uipagecontrol *)pagecontrol { 
 if (!_pagecontrol) { 
  _pagecontrol = [[uipagecontrol alloc] init]; 
  _pagecontrol.numberofpages = self.imagearr.count; 
  _pagecontrol.enabled = no; 
  _pagecontrol.currentpage = 0; 
  _pagecontrol.hidesforsinglepage = yes; 
  _pagecontrol.pageindicatortintcolor = [uicolor whitecolor]; 
  _pagecontrol.currentpageindicatortintcolor = maincolor; 
 } 
 return _pagecontrol; 
} 
 
 
#pragma mark ------------ uiscrollviewdelegate -------- 
 
- (void)scrollviewdidscroll:(uiscrollview *)scrollview { 
 if (self.timeranimation) { 
  return; 
 } 
 cgfloat offscale = scrollview.contentoffset.x - offset_max; 
 if (offscale < 0) { 
  //右滑 
  self.leftiamgeview.layer.transformscale = 1 + 1.0/9*(fabs(offscale)/offset_max); 
  self.middleimageview.layer.transformscale = 1 - 0.1*(fabs(offscale)/offset_max); 
 } else { 
  //左滑 
  self.rightimageview.layer.transformscale = 1 + 1.0/9*(fabs(offscale)/offset_max); 
  self.middleimageview.layer.transformscale = 1 - 0.1*(fabs(offscale)/offset_max); 
 } 
  
} 
 
- (void)scrollviewdidenddragging:(uiscrollview *)scrollview willdecelerate:(bool)decelerate { 
 cgpoint offset = scrollview.contentoffset; 
  
 self.offsetx = offset.x; 
  
 if ((fabs(self.offsetx-offset_max) >= offset_max*0.5)) { 
  if (!decelerate) { 
   //替换图片 
   [self exchangeimage]; 
  } 
 } else { 
  //回弹复位 
  [scrollview setcontentoffset:cgpointmake(offset_max, 0) animated:yes]; 
  self.leftiamgeview.layer.transform = catransform3didentity; 
  self.middleimageview.layer.transform = catransform3didentity; 
  self.rightimageview.layer.transform = catransform3didentity; 
 } 
} 
 
- (void)scrollviewdidenddecelerating:(uiscrollview *)scrollview { 
 //替换图片 
 [self exchangeimage]; 
} 
 
#pragma mark ---------- exchangeimage ------ 
//替换图片 
- (void)exchangeimage { 
 if (self.offsetx-offset_max < 0) { 
  //右滑 
  uiimage *rightimage = self.rightimageview.image; 
  self.rightimageview.image = self.middleimageview.image; 
  self.middleimageview.image = self.leftiamgeview.image; 
  self.leftiamgeview.image = rightimage; 
   
  if (self.pagecontrol.currentpage - 1 < 0) { 
   self.pagecontrol.currentpage = self.pagecontrol.numberofpages-1; 
  } else { 
   self.pagecontrol.currentpage -= 1; 
  } 
   
 } else { 
  //左滑 
  uiimage *leftimage = self.leftiamgeview.image; 
  self.leftiamgeview.image = self.middleimageview.image; 
  self.middleimageview.image = self.rightimageview.image; 
  self.rightimageview.image = leftimage; 
   
  if (self.pagecontrol.currentpage + 1 >= self.pagecontrol.numberofpages) { 
   self.pagecontrol.currentpage = 0; 
  } else { 
   self.pagecontrol.currentpage += 1; 
  } 
 } 
 [self.scrollview setcontentoffset:cgpointmake(offset_max, 0)]; 
 self.leftiamgeview.layer.transform = catransform3didentity; 
 self.middleimageview.layer.transform = catransform3didentity; 
 self.rightimageview.layer.transform = catransform3didentity; 
} 
 
#pragma mark ---------- timer -------- 
- (void)timeraction { 
 self.offsetx = kscreenwidth+offset_max-64; 
 
 self.timeranimation = yes; 
 [uiview animatewithduration:0.8 animations:^{ 
  [self.scrollview setcontentoffset:cgpointmake(self.offsetx, 0)]; 
  self.rightimageview.layer.transformscale = 10/9.0; 
  self.middleimageview.layer.transformscale = 0.9; 
 } completion:^(bool finished) { 
  self.timeranimation = no; 
  [self exchangeimage]; 
  self.rightimageview.layer.transform = catransform3didentity; 
  self.middleimageview.layer.transform = catransform3didentity; 
 }]; 
} 
 
@end 

self.scrollview = [[customscrollview alloc] initwithframe:cgrectmake(0, 0, kscreenwidth, 170)]; 
[self.view addsubview:self.scrollview];