import

/**
UITextView with placeholder support
*/
@interface IQTextView : UITextView

/**
Set textView's placeholder text. Default is nil.
*/
@property(nullable, nonatomic,copy) IBInspectable NSString *placeholder;

@end
UITextView.M文件

//
// IQTextView.m
// https://github.com/hackiftekhar/IQKeyboardManager
// Copyright (c) 2013-16 Iftekhar Qurashi.
//
// Permission is hereby granted, free of charge, to any person obtaining a copy
// of this software and associated documentation files (the "Software"), to deal
// in the Software without restriction, including without limitation the rights
// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
// copies of the Software, and to permit persons to whom the Software is
// furnished to do so, subject to the following conditions:
//
// The above copyright notice and this permission notice shall be included in
// all copies or substantial portions of the Software.
//
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
// THE SOFTWARE.

import "IQTextView.h"

import

@interface IQTextView ()

-(void)refreshPlaceholder;

@end

@implementation IQTextView
{
UILabel *placeHolderLabel;
}

@synthesize placeholder = _placeholder;

-(void)initialize
{
[[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(refreshPlaceholder) name:UITextViewTextDidChangeNotification object:self];
}

-(void)dealloc
{
[[NSNotificationCenter defaultCenter] removeObserver:self];
}

(instancetype)init
{
self = [super init];
if (self) {
[self initialize];
}
return self;
}

-(void)awakeFromNib
{
[super awakeFromNib];
[self initialize];
}

-(void)refreshPlaceholder
{
if([[self text] length])
{
[placeHolderLabel setAlpha:0];
}
else
{
[placeHolderLabel setAlpha:1];
}

[self setNeedsLayout];
[self layoutIfNeeded];

}

(void)setText:(NSString *)text
{
[super setText:text];
[self refreshPlaceholder];
}

-(void)setFont:(UIFont *)font
{
[super setFont:font];
placeHolderLabel.font = self.font;

[self setNeedsLayout];
[self layoutIfNeeded];

}

-(void)setTextAlignment:(NSTextAlignment)textAlignment
{
[super setTextAlignment:textAlignment];
placeHolderLabel.textAlignment = textAlignment;

[self setNeedsLayout];
[self layoutIfNeeded];

}

-(void)layoutSubviews
{
[super layoutSubviews];

CGFloat offsetLeft = self.textContainerInset.left + self.textContainer.lineFragmentPadding;
CGFloat offsetRight = self.textContainerInset.right + self.textContainer.lineFragmentPadding;
CGFloat offsetTop = self.textContainerInset.top;
CGFloat offsetBottom = self.textContainerInset.bottom;

CGSize expectedSize = [placeHolderLabel sizeThatFits:CGSizeMake(CGRectGetWidth(self.frame)-offsetLeft-offsetRight, CGRectGetHeight(self.frame)-offsetTop-offsetBottom)];
placeHolderLabel.frame = CGRectMake(offsetLeft, offsetTop, expectedSize.width, expectedSize.height);

}

-(void)setPlaceholder:(NSString *)placeholder
{
_placeholder = placeholder;

if ( placeHolderLabel == nil )
{
    placeHolderLabel = [[UILabel alloc] init];
    placeHolderLabel.autoresizingMask = (UIViewAutoresizingFlexibleWidth|UIViewAutoresizingFlexibleHeight);
    placeHolderLabel.lineBreakMode = NSLineBreakByWordWrapping;
    placeHolderLabel.numberOfLines = 0;
    placeHolderLabel.font = self.font;
    placeHolderLabel.textAlignment = self.textAlignment;
    placeHolderLabel.backgroundColor = [UIColor clearColor];
    placeHolderLabel.textColor = [UIColor colorWithWhite:0.7 alpha:1.0];
    placeHolderLabel.alpha = 0;
    [self addSubview:placeHolderLabel];
}

placeHolderLabel.text = self.placeholder;
[self refreshPlaceholder];

}

//When any text changes on textField, the delegate getter is called. At this time we refresh the textView's placeholder
-(id)delegate
{
[self refreshPlaceholder];
return [super delegate];
}

@end

UITextView的placeHolder

import

import "IQTextView.h"

import

import

import

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